WASHINGTON — Facing mounting criticism for blocking proposals to bolster election security, Senator Mitch McConnell on Thursday threw his weight behind a new infusion of $250 million to help states guard against outside interference in the 2020 voting.
Mr. McConnell, Republican of Kentucky and the majority leader, has been under regular attack from both Democrats and a conservative group for refusing to allow the Senate to vote on various election security proposals, some of them bipartisan, despite dire warnings from the intelligence community that Russia is already trying to replicate the elaborate meddling campaign it carried out during the 2016 presidential contest.
The additional funding, Mr. McConnell said in announcing his support, “will bring our total allocation for election security — listen to this — to more than $600 million since fiscal 2018.” The money was quickly approved by the Appropriations Committee later Thursday.
Though Mr. McConnell has embraced other seemingly derogatory nicknames over the years, he was incensed at being called “Moscow Mitch” by those who claimed his opposition showed he was willing to accept foreign election interference because it had benefited his own party by helping to elect President Trump, despite the senator’s long record of taking a hard line against Russia.
Aides said that the criticism had not driven Mr. McConnell’s decision to back the measure, and that he had always planned to support new money for state election offices as part of the annual spending bills now working their way through Congress. He and other Republicans, wary of too much federal intervention in state-run elections, preferred providing the new money without new federal requirements that could be added in legislation being pushed by Democrats, they said.
Still, Senate Republicans had previously opposed similar proposals. On Thursday, they said the increase was a way to reassure the public that the states would have the resources they needed to protect the integrity of their elections.
“While different states have used this money in different ways — and some states frankly haven’t used it all — generally this money has moved the states toward much more security than they otherwise would have had,” said Senator Roy Blunt, Republican of Missouri and the chairman of the Rules Committee.
Democrats and activist groups who favor more money have also pushed for sweeping election overhauls circulating in the House and the Senate. But they still welcomed what they painted as a sudden change of heart from Mr. McConnell.
“Leader McConnell kept saying we don’t need the money,” said Senator Chuck Schumer of New York, the minority leader. “But now, thank God, he has seen the light.”
“If Americans don’t believe their elections are on the up-and-up, woe is us as a country and as a democracy,” Mr. Schumer said. “It is not all the money we requested, and it doesn’t include a single solitary reform that virtually everyone knows we need, but it’s a start.”
States would be allowed to use the money in various ways, but part of the federal effort is to make certain that all of them have a voting system in place that includes a way for results to be audited. The added money was included in a bipartisan proposal offered by the two leaders of the Appropriations Committee, Senator Richard C. Shelby, Republican of Alabama and the chairman, and Senator Patrick J. Leahy of Vermont, the senior Democrat, along with Senator Chris Coons, Democrat of Delaware.
Other members of the panel hailed it as a potential breakthrough that could lead to more election security measures being advanced by Congress.
“Elections are the bedrock of our democracy, and Congress has a patriotic duty to protect them,” said Senator Jeanne Shaheen, Democrat of New Hampshire. “In addition to funding, there are many steps that Congress needs to take to make sure foreign adversaries don’t have free rein to interfere in our democratic process.”
In opposing the other election overhauls, Mr. McConnell has criticized them as Democratic attempts to gain a partisan advantage. He also argued that many new protections had already been put in place since 2016, and that the 2018 election showed that they were working.
“The Trump administration has made enormous strides to help states secure their elections without giving Washington new power to push the states around,” Mr. McConnell said.
Still, the embrace of the new allocation showed that the attacks on Mr. McConnell and his Republican colleagues over election security were effective enough to shake loose a substantial amount of additional money, leaving open the possibility that the funding could even increase as the Senate enters final spending negotiations with the Democratically controlled House.