WASHINGTON — In a surprise development, Senate Majority Leader Mitch McConnell announced his support Thursday for additional money to bolster the country's election system ahead of the 2020 vote, a move that counters his earlier position resisting calls for more funding.

McConnell, R-Ky., said he is co-sponsoring an amendment to an appropriations bill that would provide $250 million for election security.

"I'm proud the Financial Services & General Government bill will include a bipartisan amendment providing another $250 million for the administration and security of their elections, to help states improve their defenses and shore up their voting systems," McConnell said. "I am proud to have helped develop this amendment and to co-sponsor it in committee."

McConnell's backing comes after Democrats have been putting political pressure on him and Republicans for more than a year to get behind additional provisions, including new funding, to protect against hacking and interference in the elections.

"This morning, after months and months and months of Republican resistance, and months of insistent Democratic pressure, Senate Republicans have finally agreed to support our Democratic request for additional election security funding in advance of the 2020 elections," Senate Minority Leader Chuck Schumer, D-N.Y., said on the Senate floor.

Democrats brought up a similar measure last year that would have also provided an additional $250 million to the states, but McConnell and most Republicans opposed it. A senior Republican leadership aide said the measure was brought up when states still had not determined how they'd spend the $380 million they were given in 2018.

In July, Democrats attempted again to bring election security legislation to the floor. McConnell's opposition to the measure that would have made broad changes to the election system led in part to critics giving him the moniker of "Moscow Mitch."

Republicans pointed to an election briefing by intelligence officials in July as the reason that more money wasn't necessary.

"All the money hadn't been spent that we gave to the states," Sen. Richard Burr, R-N.C., chair of the Senate Intelligence Committee, told NBC News at the time, referring to funds granted to the states ahead of the 2018 elections.

Now that McConnell is backing the funding, Democrats and election security experts say that $250 million is a good start but not enough.

Sen. Mark Warner, D-Va., vice chair of the Senate Intelligence Committee, which wrote a report on the security vulnerabilities in the 2016 election, said that $250 million is a "necessary but not sufficient part of securing our elections against foreign attack."

Aaron Scherb, director of legislative affairs at Common Cause, said that far more is needed to secure the election system.

"Providing $250 million in additional election security funding is like asking an army to go fight a war with horses and bayonets," Scherb said.

The House passed a bill that would give states almost three times more — $600 million.

A Republican senator on background acknowledges that this $250 million is a fig leaf, Republicans’ attempt to keep Democrats from obtaining the hundreds of millions more they want for election security.

"What changed for some people was that Democrats would probably pass an amount of money that was substantially bigger," the senator said.