From the moment it first surfaced, Democrats have panned a proposal by Louisiana GOP Sen. David Vitter to essentially end employer health care contributions for members and staff under Obamacare, and that hasn’t changed despite the fact it might sound good outside the Beltway.

House Republicans are expected to include a version of the Vitter amendment in their next attempt to further amend the “clean” stopgap spending measure favored by Democrats. That continuing resolution would keep the  government fully operational past midnight tonight, but with the House continuing to insist on amendments, a shutdown appears likely.

Senate Democrats say, like the health care amendments they killed earlier in the day, the House’s third attempt to undermine the president’s signature legislative achievement will go nowhere, except maybe onto the imaginary “table” where unwanted proposals gather dust. (The Senate will likely vote to table or kill the House’s next salvo, as they did earlier Monday.)

“Let me make something really clear: No United States senator is forced in any way from taking a large employer contribution for their health care,” said Sen. Barbara Boxer, D-Calif. “Sen. Vitter today, yesterday and several years ago could have said ‘I don’t want this employer benefit’ and could have sent the check back to the Treasury. He could also call in his staff and say, ‘I’ve been thinking about it. I don’t think you deserve to have an employer contribution to your health care. Therefore, your pay will now be reduced to equal the size of your contribution, and I am sending it back to the Treasury.'”

Vitter has filed two ethics complaints against Boxer in connection with the debate over his amendment, which is especially notable because Boxer also serves as chairwoman of the Ethics Committee.

The Office of Personnel Management on Monday released a final rule for publication in the Federal Register that explains how the provisions requiring lawmakers and staff to access the new exchanges instead of the Federal Employee Health Benefits Plan will work.

To maintain employer contributions, the employees will need to participate in the D.C.-based small business exchange.

Despite Democratic objections, Republican advocates of the amendment insist that if it became the only extra provision in the otherwise agreed upon continuing resolution, it would put Democrats in an untenable position.

“I think our language is the best thing in sight to avoid a shutdown, quite frankly,” Vitter said. “If our language is there, and that’s what Democrats have to hang their hat on to say no, I think they’re on completely indefensible ground.”

“If in a day or two, the Democrats are refusing to continue to fund government only because of this provision protecting themselves, then I think they will be correctly perceived for what they’re doing, and we’ll be on solid ground in that scenario,” Vitter added.

Of course, Iowa Republican Sen. Charles E. Grassley, the author of the language that requires lawmakers and staff to buy their health care on the exchanges, said last week he never intended for staffers to lose the employer contributions.

Asked if their own staff might ponder leaving as a result of the amendment being adopted, the lawmakers backing the proposal said that those in their offices understood the health care law itself eliminated the contributions. Sen. Ron Johnson, R-Wis., noted that several of his aides had signed on to comments made to OPM that could form the basis for a lawsuit.

Rep. Ron DeSantis, who is leading the effort in the House, agreed with the sentiments of Vitter and Johnson. The Florida Republican spoke at a joint news conference outside the Capitol with the duo and Sen. Michael B. Enzi, R-Wyo.

“You can’t just magically create subsides through executive fiat,” said DeSantis. “My staff understands that it’s legally unsustainable in terms of what OPM tried to do. So, they don’t view it as me trying to take something away. They understood Obamacare did that, and it was just a matter of time before this day came.”