McCaskill worked behind the scenes to end the shutdown. Republicans blame her anyway. | McClatchy Washington Bureau

Missouri Sen. Claire McCaskill broke with her fellow Democrats to oppose a government shutdown late Friday, then spent her weekend in meetings on Capitol Hill and on the phone trying to end it.

But Republicans eager to oust her in 2018 are trying hard to blame her for the shutdown anyway.

Within minutes of Monday’s Senate vote to limit debate on a measure to reopen the government, the Republican National Committee blasted out an email: “After three days of a Schumer Shutdown, only one question remains for Senator Claire McCaskill: What was the point?”

McCaskill is widely considered the most endangered Senate Democrat this year as she seeks her third term in a state President Donald Trump won by nearly 19 percentage points.

She was one of only five Democratic senators who sided with Republicans in Friday night’s closely-watched vote to curb debate on a stopgap spending plan. That seemed like a reasonable way of assuaging moderate Republicans and independents in her state, centrists she badly needs to win a third term.

Her vote Friday even drew praise from Majority Leader Mitch McConnell, R-Ky., who lauded the five red-state Democrats on the Senate floor for bucking their own party.

“There were five courageous Democrats on the other side who stood up to this ridiculous argument that it made sense somehow to shut down the government over an illegal immigration issue that the vast majority of this body would like to do something about anyway,” McConnell said.

But the Republican spirit of cooperation fizzled quickly. In the wee hours of Saturday morning, McCaskill offered a plan that would have ensured that troops continued to receive pay and benefits despite the shutdown. McConnell objected and the measure died.

McCaskill also backed legislation Friday that would have prevented lawmakers in Congress from receiving pay during shutdowns and vowed to donate her own pay to charity until the government reopened.

As the impasse dragged into the weekend, McCaskill participated in both in-person and via telephone diplomacy on Capitol Hill. She shuttled between meetings of Republican and Democratic senators led by her close personal friend, Sen. Susan Collins, R-Maine, and other discussions with fellow Democrats led by Minority Leader Chuck Schumer, D-N.Y., another close friend.

McCaskill played an instrumental role in negotiations and was “very constructive,” said Collins in an interview on Monday.

“She came very faithfully to the very long meetings we had the last few days over the weekend despite recovering from the flu,” Collins said. “She was helpful in talking about the harm that the shutdown would do to our military in particular and she kept reminding people of that fact to urge them to come to a compromise.”

McCaskill spent Saturday night and most of Sunday on the phone with her Senate colleagues, trying to drum up support for a deal, said her spokesman John LaBombard.

After the shutdown ended, McCaskill tweeted, “I am so encouraged that a large bipartisan group of Senators worked TOGETHER to help make it happen. Proud to be a part of that.”

Republicans piled on anyway.

The National Republican Senatorial Committee began running auto-play Facebook ads targeting McCaskill immediately after the shutdown began Saturday morning. The ads were part of a national campaign aimed at punishing red-state Democrats for the shutdown, regardless of how they they voted.

“The Schumer Shutdown will have serious, real world consequences for Missouri children and seniors, as well as our national security,” said NRSC spokesman Bob Salera. “Missouri voters will hold Claire McCaskill responsible for this unnecessary shutdown forced by the Democrats.”

Missouri Attorney General Josh Hawley, the GOP’s top recruit to challenge McCaskill, accused the senator of not doing enough to prevent the shutdown.

He called on McCaskill to condemn every single senator in her party who voted for the shutdown. “The reality is that she cares more about which way the political winds are blowing than doing what is right for the people she serves,” he said. “This didn’t need to happen.”

Hawley’s campaign did not respond to questions from McClatchy’s Kansas City Star about whether he supported a legal path to citizenship for so-called Dreamers, the young undocumented immigrants who came to the U.S. as children.

McCaskill supports a legislative solution for Dreamers, but has said she wasn’t willing to “draw lines in the sand” over government funding.

Had the shutdown continued, the fallout could have hurt McCaskill and other Democrats running in states Trump won.

A recent CNN poll from the week before the shutdown showed Democrats’ advantage over Republicans in the lead-up to this year’s midterm elections already was narrowing. The poll showed a 49 percent to 44 percent margin in favor of Democrats among registered voters, a big drop from the double-digit leads Democrats held over Republicans in the past three months.

The poll also found that 56 percent of registered voters believed that approving a budget agreement to avoid a shutdown is more important than continuing the DACA program.