Susan Collins, the moderate US senator from Maine whose vote to put Brett Kavanaugh on the supreme court was decisive, despite sexual assault allegations against the nominee, defended herself on Sunday against charges of betraying women and the #MeToo movement – as the Republican leader, Mitch McConnell, boasted that the bitter fight on Capitol Hill had given his party a late advantage in the forthcoming midterm elections.

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A day after Justice Kavanaugh, as he is now titled, was granted the ninth seat on the nation’s highest court, in the face of fierce protests, Collins was asked by Dana Bash on CNN’s State of the Union whether she had betrayed women. The Republican senator replied: “This is a case where there was an incident that happened allegedly 36 years ago where there is no corroborating evidence.”

She went on: “It is not fair to Brett Kavanaugh for this to be disqualifying in the absence of evidence, but that does not mean that I don’t believe Christine Ford was a victim of sexual assault.”

Collins then put further space between herself and Ford, the California-based professor who accused Kavanaugh of attempting to rape her at a teenage gathering in Maryland in the early 1980s. She said that she found Ford’s testimony before the Senate judiciary committee “heartwrenching, painful, compelling” but she went on to say: “I believe that she believes what she testified to.”

But the Democratic Hawaii senator Mazie Hirono shot back at Collins’s phrase, asking: “What is that?” on CNN, and calling it insulting to Ford.

With the dust barely settling after a process that was meant to uphold the sanctity and august bearing of the supreme court but ended up being one of the most partisan, and narrowly won, confirmation proceedings in history, brickbats continued to fly over the weekend. Thousands of women and men rallied outside the court on Saturday in protest.

Facebook Twitter Pinterest Protesters fill the stairs at the east steps of the US Capitol against the confirmation of associate justice nominee Brett Kavanaugh on Saturday. Photograph: UPI/Barcroft Images

On Sunday, the Senate majority leader, Mitch McConnell, told Fox News Sunday that getting Kavanaugh on to the bench is his proudest accomplishment in Congress. He told CBS that the fight put up by Democrats against the judge had simply energized Republican voters for the November midterm elections who had previously been less motivated than Democrats. “So I want to thank the other side,” he said. Hehad said after the confirmation vote on Saturday afternoonthat: “These things always blow over.” But bitter divisions in Congress and the country are almost certain to continue.

Much of the public anger late in the battle was directed at Collins who swung behind Kavanaugh in the end, unlike her peer, Senator Lisa Murkowski from Alaska, who was the lone Republican “No” during the procedural vote on Friday that paved the way for a smooth final Senate vote on Saturday afternoon. The political wing of the women’s health organization Planned Parenthood, which has been a firm ally of Collins in the past and even presented her with an award, put out a devastating statement in which it said: “Senator Collins has made it clear that she can no longer call herself a women’s rights champion. She has sided with those who disbelieved, disrespected, and even mocked survivors.”

Collins told CBS’s Face the Nation that former president George W Bush phoned her three times to talk up Kavanaugh, who worked at the Bush White House. She said pressure from both sides had been “overwhelming”.

Play Video 3:24 Key moments from Brett Kavanaugh's confirmation battle – video report

A crowd-sourced fund set up this weekend to try to unseat Collins when she comes up for re-election in 2020 has attracted more than $2m. On Friday, Susan Rice, former national security adviser to Barack Obama when he was president, hinted that she was considering running for the Maine seat.

Collins hit back at Rice on Sunday with a snarky remark about her potential rival’s connections to Maine. “As far as Susan Rice is concerned, her family has a house in Maine, but she doesn’t live in Maine and everybody knows that.” And in a dig that online commentators saw as Trump-like in its tone, Collins added sarcastically that when Rice was nominated as ambassador to the United Nations in the Obama administration “she came to me and pleaded with me to introduce her” to a key Senate committee.

Hirono, however, concluded with: “I want to ask Susan Collins, if you were interviewing someone for a lifetime position to some company would you hire somebody with this kind of cloud over their heads?”

Meanwhile Heidi Heitkamp, a Democratic senator who voted against Kavanaugh despite representing the deeply conservative state of North Dakota, where her seat is now in serious jeopardy, put out a new TV ad in which she states: “I don’t think he told the truth” and in any case he was “too biased to be impartial”.

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The confirmation was completed just a month before the midterms. McConnell told CBS that the Kavanaugh fight had galvanized conservatives in ways Trump’s tax cuts and trade wars had failed to do.

McConnell admitted that until the supreme court dispute, his party had a problem going into the midterms. “Everybody knows how energized the Democrat side is, and so our energy and enthusiasm was lagging behind theirs until this. I think this gave us the motivation to have the kind of turnout in the election that will help us hold the Senate.”

The new conservative-leaning majority on the court could have an impact soon if any of the dozens of federal lawsuits filed against the Trump administration by Democratic-leaning states make it to the bench, concerning issues such as vehicles emissions, immigration and internet access.