hermosawave/iStockBy KENDALL KARSON, ABC News

(WASHINGTON) -- The presidential primary comes to an end on Tuesday, with Connecticut bookending a primary season that has spanned more than half the year -- another reflection of the reach of the coronavirus' impact on the 2020 election.

Despite the relatively low-key races in the Constitution State, voters in Georgia, Minnesota, Vermont and Wisconsin are also heading to the voting booth for runoff elections or statewide primaries that bring some high stakes for the rest of the ballot.

A candidate who has espoused racist, anti-Semitic, Islamaphobic views and supported the QAnon conspiracy theory is one runoff election away from becoming the Republican nominee in Georgia's 14th Congressional District. Rep. Ilhan Omar, a member of the freshman "squad," faces a tough primary challenge in her deep blue Minneapolis district. Meanwhile, Wisconsin and Georgia, two states whose earlier primaries were plunged into chaos amid the coronavirus, are set to reattempt running elections as the pandemic continues.

Here are four things to watch on Tuesday:

The end of the primary season -- for the presidential race

Connecticut's contest closes out a presidential primary that landed in a far different place from where it began. Former Vice President Joe Biden, who was on the ropes throughout the first month of voting in February, is now the presumptive nominee. In-person campaigning is nearly non-existent less three months before November's election, after the coronavirus outbreak upended the election. And now the primary process ends two months after it was intended to finish out.

Voters in Connecticut will be the last to weigh in on the Democratic and Republican presidential primaries that have been settled for months, but still, Tuesday provides election officials with a much-needed test-run ahead of the fall.

Election officials implemented a massive push for vote-by-mail in a state that historically has been resistant to changing its electoral process -- and a similar blueprint is planned for the fall.

Gov. Ned Lamont signed an emergency order allowing for all voters to use absentee ballots -- a departure from previous elections in a state that typically limits absentee voting to only those who are out of state for election day or physically incapable of getting to the polls. And Secretary of State Denise Merrill mailed applications to all registered Republican and Democratic voters -- a total of 1.2 million -- at the end of June.

In-person voting will also be available on Tuesday, and polling locations are expected to undergo deep cleanings to safeguard voters and election workers from the risks of the virus. And for those seven polling locations still without power in the aftermath of Hurricane Isaias of the 748 polling places statewide, the secretary of state's office confirmed to ABC News on Monday that all seven are using generators to provide them with power to run smooth elections.

Will Georgia Republicans boost a QAnon backer?

In Georgia's 9th Congressional District, which is one of the most conservative in the state, the race to replace Rep. Doug Collins features primary runoffs for both parties. The seat is now up for grabs after Collins, who is one of President Donald Trump's staunchest allies in Congress, opted to run in the Senate special election instead. Tuesday's race will likely determine the solid red district's next member of Congress.

Matt Gurtler, a state lawmaker representing the 8th district in the state House since 2016, is squaring off against Andrew Clyde, who served in the U.S. Navy for 28 years and deployed on three combat missions to Kuwait and Iraq. Gurtler has earned the endorsement of Sen. Rand Paul, R-Ky., and was the top vote-getter in the crowded June primary, topping Clyde by 3,533 votes, when nine candidates were on the ballot, and the majority of the votes were cast for the other seven candidates.

On the Democratic side, Brooke Siskin, who previously sought political office in 2012 when she ran for the state House, is facing off against Devin Pandy, who served in the U.S. Army.

Siskin received the most votes in June's three-candidate primary. Overall, the total votes cast for Democrats were dwarfed by the amount of votes cast for Republicans.

In the most closely watched primary on Tuesday, runoffs are being held in the deep red 14th Congressional District, where a controversial candidate, Marjorie Taylor Greene, a businesswoman who has embraced the QAnon conspiracy theory, could potentially be the GOP nominee. If she wins, Greene will force national Republicans to wrestle with backing another candidate who supports the fringe movement, which has roiled the party over candidates who openly embrace baseless conspiracy theories.

Greene is facing off against John Cowan, who finished second in the June primary, about 20 points behind Greene. The controversy over Greene's candidacy was ignited when POLITICO unearthed hours of Facebook videos in which Greene spewed racist, anti-Semitic and Islamaphobic views; falsely accused Democratic megadonor and Holocaust survivor George Soros of collaborating with Nazis; said that white men "are the most mistreated group of people" in the country; and targeted Omar, a Muslim, over her religion, saying that members of Congress shouldn't be allowed to be sworn in on the Quran.

While some members of Congress condemned Greene and endorsed Cowan after POLITICO's reporting, including House Majority Whip Steve Scalise, others have stood by their endorsements, including the House Freedom Caucus's fundraising arm and Ohio Rep. Jim Jordan. Minority Leader Kevin McCarthy condemned her comments, but as of last week, McCarthy was "remaining neutral" in the race.

Greene was initially running the 6th Congressional District -- a battleground seat currently held by Democrat Lucy McBath -- but she abandoned that bid in late December after Rep. Tom Graves, a Republican, announced he was retiring after holding the seat for a decade.

Omar's fight tests party's liberal wing

A week after Michigan Rep. Rashida Tlaib silenced any doubts about her re-election -- securing a 30-point margin of victory in her Detroit district -- another member of the "squad," is poised to defend her seat on Tuesday in one of the most expensive primary campaigns in the state.

Omar, who gained national prominence as a progressive firebrand, has been battling various controversies since she arrived in Washington in 2018. Antone Melton-Meaux, a Black lawyer and mediator, has emerged as Omar's most serious challenger in the Minnesota 5th district race, which includes Minneapolis and its suburbs.

Larry Jacobs, a professor of political science at the University of Minnesota, said that he expected Omar to face a tough fight, but he still expects her to "prevail" if turnout is in her favor because she is a progressive in a progressive district and she has experience running campaigns, whereas Melton-Meaux is "new to politics."

"All those things most of the time give you a win for the incumbent," Jacobs told ABC News, but added that the overarching storyline in this race is how did "someone who has all those things going in her favor end up in a dogfight."

Both Omar and Melton-Meaux have each raised over $4 million in donations. The large majority of Omar's fundraising comes from small individual donations. Much of Melton-Meaux's funds, however, have stemmed from large donors and from pro-Israel political action committees.

Both candidates have gained a number of notable local and national endorsements. Last week, the Minneapolis Star Tribune put their support behind Melton-Meaux, while prominent Democrats like House Speaker Nancy Pelosi, D-Calif., Sen. Bernie Sanders, I-Vt., and Minnesota Gov. Tim Walz backed Omar.

Jacobs said there's a lot of "uncertainty" on both sides, but it is still "possible" for Melton-Meaux to win. Many will be voting by mail in Minnesota due to the COVID-19 pandemic. Jacobs said that if there's a clear winner he expects the results to be known "within a day or two," but if it's a very close race, "it could stretch on for weeks."

In nearby Wisconsin, another incumbent Democrat is facing a primary challenge in the 3rd Congressional District. Rep. Ron Kind, one of 30 Democrats in a Trump-won district in western Wisconsin that borders Minnesota, is up against Mark Neumann, a doctor, Franciscan friar and missionary, who is seeking to out-flank him from the left.

Meanwhile, back in Minnesota, Republicans are hoping to flip a Democratic-held seat in Minnesota's 7th district, where Trump won by a large margin in 2016.

Five Republicans are vying for the GOP nomination to challenge incumbent Rep. Collin Peterson, a conservative Democrat who has held his seat in Congress since 1991, but who has been losing support in an increasingly conservative district.

The crowded field includes former-Lt. Gov. Michelle Fischbach, who was endorsed by Trump in March, and retired Air Force Maj. Dave Hughes, who won the Republican primary in 2016 and 2018, but failed to unseat Peterson.

"I would say (Fischbach's) got to be the favorite because she has name recognition and she does have the support of the Republican Party," Jacobs said.

Hughes was endorsed by Trump in September 2018 but last December, the Trump campaign called on the Republican to stop touting Trump's 2018 endorsement.

In the state's Senate race, Jacobs said that neither incumbent Democratic Sen. Tina Smith, nor her Republican challenger Jason Lewis are expected to face any real "action" in their primary battles and they have their eyes set on the general election.

Take 2 for pandemic elections

Both Wisconsin and Georgia are aiming to run far smoother elections than those held in the spring and early summer. They were some of the cycle's messiest primaries and foreshadowed potentially graver challenges awaiting in the fall.

Election officials in both states have implemented significant changes to avoid the problems that plagued their ability to conduct elections earlier this year.

In battleground Wisconsin, which was one of the first to hold an election during the pandemic, officials appeared to be learning from what went wrong the last time around.

In Milwaukee, the state's largest city, there will be 168 polling locations on election day, according to the city election commission, a sharp increase from the five that were available for the April 7 primary. There are typically 180 polling sites that are operational on election day in the city. In Madison, the second largest city in the state, there will be 86 polling locations on Tuesday, an uptick from the 66 that were used in April, and only slightly down from the 92 used normally.

Similar to April, the National Guard is being deployed to assist at in-person polling sites as poll workers. Those sites will also have proper sanitation and social distancing procedures in place.

To avoid ballots not arriving in time, state election officials are encouraging voters to drop their absentee ballots at drop-boxes or their normal polling place on election day, rather than through the mail since the U.S. Postal Service advised that it can take up to one week for mail to be delivered, according to the chief elections official Meagan Wolfe. So far, 903,760 ballots have been requested by Wisconsin voters, and 507,709 have been returned, which is already nearly five times the absentee ballot total from 2018 and more than six time the total from 2016.

In Georgia, the runoffs will be held in 94 of the state's 159 counties on Tuesday. That includes a district attorney race in Fulton County, where 70% of the June 9 primary problems took place. It will offer election officials a second chance at a dress rehearsal ahead of November.

For the June primary, Secretary of State Brad Raffensperger, a Republican, opted to send all 6.9 million active registered voters absentee ballot applications, and from that, his office created "rollover lists." Anyone who is 65 or older, or disabled will get an absentee ballot mailed to them for the rest of this election cycle. That amounted to about 505,000 voters statewide, and 327,000 of those voters reside in the counties holding runoff elections, Sterling said. Those ballots are mailed by the secretary's office.

With the secretary of state's office blaming most of the issues stemming from the June primary on the lack of poll worker training as opposed to technical issues with the machines, they have since "trained hundreds of field techs" who will be deployed in the four biggest counties -- Fulton, DeKalb, Gwinnett and Cobb -- and Chatham, which is home to Savannah, where 93% of the problems were on June 9.

Ahead of the primary, Raffensperger's office distributed thousands of gallons of hand sanitizer and hundreds of thousands of gloves and reusable face masks for poll workers to the counties, and that supply is expected to be used for the runoffs as well. His office also distributed signage explaining social distancing measures and gave guidance regarding how to manage lines.

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