WASHINGTON (Reuters) - More than three years have passed since former President Donald Trump's supporters stormed the U.S. Capitol on Jan. 6, 2021, trying to overturn his election defeat, but the event will play a major role in a series of congressional primaries on Tuesday.

The riot played a major role in the life of two candidates seeking their parties' nominations to run for the U.S. House of Representatives -- Democratic former Capitol Police officer Harry Dunn of Maryland and West Virginia Republican Derrick Evans, who served time in prison after pleading guilty to joining the unrest.

Both are seeking their party's nominations in highly partisan districts that are seen as unlikely to be competitive in the Nov. 5 general election, when Republicans will be defending a narrow House majority. That means the winners of those two primaries will likely serve in Congress beginning next year.

In a third state, Nebraska, moderate Republican Representative Don Bacon is seeking re-election after risking his political future by working in a bipartisan manner with Democrats, including on a vote to certify the results of the 2020 election.

Trump continues to falsely claim that his 2020 loss to Democratic President Joe Biden was the result of fraud.

Dunn, 40, is one of 22 Democrats running to succeed the retiring Representative John Sarbanes. He has led the field in fundraising and has secured an endorsement from former House Speaker Nancy Pelosi, with polling suggesting the race will be competitive between him and Sarah Elfreth, a state senator.

Dunn was shoved into the spotlight when he testified to Congress about the attack, describing how rioters taunted him with racial slurs during the riot as they attempted to overturn the results of the 2020 election.

In an interview with Reuters this month, Dunn said the events of Jan. 6 changed his life and prompted him to enter politics.

    "I would still be on the force. A whole career there. A good send-off on the (police) radio when you retire and collect my full pension. But those aren't in the cards anymore," he said.

EVANS CHALLENGES INCUMBENT

In nearby West Virginia, Evans is running in a primary against Republican incumbent Representative Carol Miller, who was among the 139 House Republicans who supported Trump's attempt to overturn his loss to Biden.

Evans, a former teacher and state legislator, served three months in prison after pleading guilty to a felony charge related to entering the Capitol illegally on Jan. 6.

Evans dubbed Miller an "undocumented Democrat" after she voted earlier this year for a bill to avert a goverment shutdown. He has also called for the completion of Trump's border wall, term limits for lawmakers and the possible dismantling of the U.S. Federal Reserve.

Miller's office has touted her endorsements from the likes of Jim Jordan, a powerful conservative who is the chairman of the House Judiciary committee, and the Susan B. Anthony List, an anti-abortion group.

In Nebraska, the moderate Bacon is facing Republican challenger Dan Frei, who says he fully supports Trump's agenda for a possible second term.

Unlike the seats in Evans' and Dunn's districts where one party is highly favored to win the general election, Bacon's district is expected to be competitive in November.

The Democratic candidate in the general election will be Tony Vargas, a former teacher, school board member and current state senator, who is running unopposed for that nomination.

In addition to the House races, voters in West Virginia will select candidates for governor. The options include Miller's son, the son of the state's senator Shelley Moore Capito and Patrick Morrisey, the state's attorney general.

Maryland will also host a U.S. Senate primary, where Prince George's County Executive Angela Alsobrooks is running against U.S. Representative and alcohol retailer David Trone for the Democratic nomination, while Larry Hogan, the state's former governor, is seeking the Republican nomination.

While Maryland has not elected a Republican senator since 1970, Hogan was popular as a governor and the polling suggests the general election could be competitive.

(Reporting by Richard Cowan and Makini Brice; Editing by Scott Malone and Alistair Bell)

By Makini Brice and Richard Cowan