They have tried to portray Ms. Klarides, who previously explored running for governor, as a left-wing reproductive rights and gun control party and questioned her solidarity with Mr Trump should he run for president again and be elected.
Ms. Levy, 65, who was nominated by Mr. Trump to be US Ambassador to Chile but whose confirmation languished in the Senate, has gone so far as to name Ms. Klarides the next Liz Cheney in a campaign e-mail. mail.
But in Connecticut, where Republicans haven’t won a national election or congressional race since 2006, Mrs. Klarides has twisted the strategy of her conservative rivals.
To oust Mr. Blumenthal from the seat he has held since 2011, Ms. Klarides has said, it takes a moderate Republican like her who has a track record of winning elections. She has expressed doubts about whether Ms. Levy and Mr. Lumaj can appeal to voters who are not affiliated with any political party, which make up Connecticut’s largest electoral bloc.
None of her opponents has ever won an election.
Mr. Lumaj, a perennial candidate who previously ran for governor, has accused Cuban-born Ms. Levy of undergoing a political transformation from a top Republican fundraiser who had previously expressed her disdain for Mr. Trump to a MAGA- candidate .
Mr. Blumenthal, 76, one of the wealthiest members of the Senate and former Attorney General of Connecticut, is known for his ubiquity at press conferences, ribbon cutting and parades. But his declining appraisal of his job’s approval comes amid an already difficult midterm election environment for Democrats.
His toughest Senate campaign was in 2010, when he defeated Linda McMahon, the professional wrestling magnate who later served in Mr. Trump’s cabinet. In that race, Mr. Blumenthal accused of misrepresenting his military service during the Vietnam War when he was a Marine Corps reservist but saw no combat. Mr Blumenthal said at the time that he never wanted to give the impression that he was a war veteran and apologized.
Mrs. Klarides has her own connection to the WWE, the entertainment giant that Mrs. McMahon has led with her husband, Vincent McMahon, who recently left the company. While studying for the bar exam after law school, Mrs. Klarides, a former model and fitness competitor, worked as a “ring girl,” placarding between rounds of wrestling matches.