Hart dropped her petition before the House panel tasked with overseeing the review, according to a statement released Wednesday, amid intense pressure from both sides.
"After many conversations with people I trust about the future of this contest, I have made the decision to withdraw my contest before the House Committee on Administration," she said, citing "the toxic campaign of political disinformation to attack this constitutional review of the closest congressional contest in 100 years."
"It is a stain on our democracy that the truth has not prevailed and my hope for the future is a return to decency and civility," she added.
GOP Rep. Mariannette Miller-Meeks was certified the winner in November by a mere six votes out of 400,000 cast, marking one of the closest House races in modern history. She was seated with the rest of Congress in early January, taking the oath of office and representing the southeastern Iowa district despite Hart moving forward with a petition in the House.
Hart asked the House panel in December to probe the results after a recount and certification, bypassing the courts and calling for a hand recount of all votes -- including 22 ballots that were excluded from the official tally. Her legal team centered their case on those excluded ballots, saying that they were legally cast and should be counted and would ultimately hand her a victory if they were included.
"Since Election Day, and throughout this entire process, my mission has been about ensuring the voices of Iowans who followed the law are not silenced. I am saddened that some Iowans’ votes will not count through no fault of their own. The work of ensuring it does not happen again will continue beyond this campaign," Hart said in the statement ending her challenge.
But a pursuit in Congress was a politically fraught maneuver, with Republicans mounting a pressure campaign against Democrats for trying to reverse the election outcome and framing the challenge as an attempt by House Speaker Nancy Pelosi try to "steal" a Republican seat and pad her slim majority.
"The race is over. I understand people get upset when they lose, but the idea that you want to come in and play a political game is concerning to me," House Minority Leader Kevin McCarthy said at a press conference in Iowa, just hours before Hart's announcement.
"We have elections and people need to have trust and faith and confidence in their elections," Miller-Meeks said earlier on Wednesday alongside McCarthy. "If six votes aren't enough to win an election, then why are six members on a committee able to overturn an election."
After Hart officially dropped her challenge, McCarthy celebrated Miller-Meeks' victory, saying in a statement, "Rita Hart and Nancy Pelosi finally heard what many Iowans told me today: Mariannette Miller-Meeks is the duly-elected Congresswoman serving Iowa’s Second Congressional District."
The GOP's efforts to cast Democrats as trying to invalidate certified election results comes after spending months supporting former President Donald Trump's attempt to reverse his electoral defeat last year. McCarthy voted alongside 138 House Republicans against certifying the presidential results from Arizona and Pennsylvania. Democrats, including Pelosi, pushed back by drawing a contrast between Hart's challenge -- which followed a legal process outlined by federal law and focused on 22 ballots to back up their claims -- and Trump's fruitless effort based on unsubstantiated allegations of fraud.
Throughout the protracted process, one of the most significant wrinkles for Democrats was within their own ranks, as some moderate members balked at the prospect of overturning the election results if a vote came to the House floor.
"Losing a House election by six votes is painful for Democrats. But overturning it in the House would be even more painful for America. Just because a majority can, does not mean a majority should," Rep. Dean Phillips, D-Minn., tweeted earlier this month.
It's not unusual for an election to be contested before the obscure committee: there have been 110 cases filed since 1933. But overturning an election is a rare outcome: over nearly 90 years, only three of those cases resulted in the declared winner being removed and replaced, according to the committee, and in one, the seat was left vacant.
New York Rep. Sean Patrick Maloney, the chair of House Democrats' campaign arm who is charged with defending Democrats' majority in next year's midterm elections, said in a statement after Hart's announcement that he respects the former Iowa state senator's decision and pledged that Democrats will continue to fight for voters.
"From the day she announced her candidacy, Rita Hart has shown that she is a tireless advocate for the people of Iowa. I respect her decision and applaud her efforts to ensure that every legal vote was counted in this election. I know her service and commitment to Iowans won't end here," Maloney said. "While Republicans have been throwing up roadblocks to the ballot box at every turn, Democrats will always fight to ensure every American can vote and that every legal vote is counted."