(Reuters) - The bitter fight over the confirmation of Supreme Court Justice Brett Kavanaugh spilled over into a key U.S. Senate race in Indiana on Monday, as the Republican challenger, Mike Braun squared off against Joe Donnelly, the Democratic incumbent.

Braun, a businessman, hammered Donnelly over his opposition to President Donald Trump’s latest nomination to the top court, seeking momentum in a race that polls show to be tight a month before Nov. 6 elections that will determine control of Congress.

Democrats need to gain a net total of two seats to win control of the Senate, which will require defending seats in several states that voted for Trump in 2016, including Indiana. Control of the Senate would allow them to block moves by Trump, including Supreme Court nominees.

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Donnelly, who is seeking a second Senate term, has been a top target of Republicans in a state Trump won by almost 20 percentage points two years ago.

“I voted against Judge Kavanaugh because of concerns about his impartiality and concerns about his judicial temperament,” Donnelly said early in the first debate between the candidates, held in Westville, Indiana, a small town in the northwest corner of the state.

Kavanaugh was accused by California university professor Christine Blasey Ford of sexual assaulting her when they were high school students in 1982. He mounted a passionate defense of his innocence in the Senate and was confirmed by 50-48 in a near-party-line vote on Saturday.

Braun’s campaign has pointed to Donnelly’s “no” vote as a lack of support for the Republican president’s agenda. On Monday, Braun charged that Donnelly was unwilling to buck his party in opposing Kavanaugh.

“Democrats including Joe Donnelly will do or say anything when it comes to their political interests,” Braun said. “It is a blood sport.”

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Republicans believe the fight over Kavanaugh has engaged conservative voters who otherwise have not been paying attention to the elections and may make a difference in several close Senate races.

WORKING WITH TRUMP

Donnelly has emphasized his ability to work with Trump, and he did so again on Monday, saying he had supported the president’s agenda the majority of the time.

Last year, Donnelly voted to confirm Trump’s first Supreme Court nominee, Neil Gorsuch. He said his vote against Kavanaugh showed independent judgment.

Read more: Indiana Democrat touts support of Trump in bid to keep seat

“Mike was for Judge Kavanaugh on the first day. If President Trump put up Bugs Bunny, Mike would have said he should go on the court,” Donnelly said. “My job is to protect the court and to put people on who are qualified.”

Braun, who served for three years in the Indiana legislature, repeatedly stressed his Trumpian “outsider” credentials. He criticized Donnelly for failing to support tax overhaul legislation that passed Congress last year and for supporting the Iran nuclear deal crafted by the Obama administration, which Trump has abandoned.

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Donnelly accused Braun of not supporting insurance coverage for pre-existing healthcare conditions in the Affordable Care Act, popularly known as Obamacare, an attack line that has been a staple of Democratic campaigns.

Braun pledged during the debate that he would never support a replacement for Obamacare “unless it covered pre-existing conditions.”

A Democrat in a Republican-heavy state, Donnelly has shown staying power, with polls largely showing him keeping a slight edge over Braun and Libertarian candidate Lucy Benton, who also participated in Monday’s debate.

He supported steel and aluminum tariffs the administration placed on imports this year, saying they benefited Indiana industries.

Donnelly has criticized other tariffs that have hurt the state’s farmers and contended they had gone too far in spurring retaliation by China. The Indiana Chamber of Commerce, which has long backed Republicans, declined in the summer to endorse anyone in the Senate race, showing the potency of the tariff issue.