Vice President-elect Mike Pence told Republicans in a private meeting Wednesday that Trump, on his first day in office, plans to take action on Obamacare through executive orders aimed at making sure the insurance marketplace isn’t disrupted by a repeal, according to Representative Chris Collins of New York, one of Trump’s earliest House GOP backers. Republicans are hoping to have a replacement plan on paper in six months, Collins said.

Related: Why Senate Democrats could help replace the ACA

On Wednesday morning, Trump warned Republicans about their tactics on the health-care issue.

“Republicans must be careful in that the Dems own the failed ObamaCare disaster, with its poor coverage and massive premium increases,” he wrote on Twitter. “Don’t let the Schumer clowns out of this web.”

“Massive increases of ObamaCare will take place this year and Dems are to blame for the mess,” he added. ”It will fall of its own weight -- be careful!”

While Trump talks of action with the speed of a tweet, things have a way of slowing down on Capitol Hill, even when party leaders and the president are on the same page.

On Wednesday, President Barack Obama and Pence visited Capitol Hill for separate meetings on the health-care bill. Obama met with Democrats to strategize over how to defend his signature initiative, while Pence talked with Republicans about the next steps in repealing and replacing it.

Obama told Democrats that he takes responsibility for not having fully communicated the potential benefits of the health-care law, according to a Democratic aide.

“Despite the negativity you have a big chunk of the country that wants this thing to succeed,” he said, according to the aide. “There are real lives at stake in this thing.”

Given Democratic opposition, Republicans plan to use a special budget procedure known as reconciliation, which is not subject to a filibuster, in hopes of putting a bill repealing much of the health-care law on Trump’s desk as soon as possible after his Jan. 20 inauguration.

The process can get messy. It starts with passage of a budget resolution with instructions to committees in each chamber, which then draft reconciliation packages. Those packages are combined into a bill that must pass both chambers. If the two versions have differences, they must be settled and passed again.

Republicans will first have to overcome a revolt from Senator Rand Paul on unrelated budget issues, with the Kentucky Republican saying Tuesday in an interview he would oppose the budget resolution because it adds significantly to the deficit.

"It never gets to balance. Not in 10 years, not in 100 years, not in 1,000," Paul said.

"Every Republican that was here voted for a balanced budget amendment to the Constitution that said it should balance in five years, but yet they are putting together a budget that never balances," he said. Paul added he isn’t swayed by the argument that the numbers don’t matter and are merely a way to fast-track the Obamacare repeal bill.

Indeed, the resolution sees the deficit rising nearly every year before hitting north of $1 trillion in 2026 alone, with the national debt hitting $29 trillion that year.

Small margin

Paul noted that until Pence is sworn in as vice president and can break ties in the Senate, a single other Republican voting no would potentially force Republicans to rewrite or delay the resolution.

Related: GOP wants Trump to trim ACA benefits, says Congress aides

As part of the process, the Senate next week will hold a vote-a-rama, where senators can call for votes on an unlimited series of amendments. That gives Democrats an opportunity to score some political points and force Republicans to take some politically awkward votes.

Senator Ben Cardin of Maryland predicted Democrats would keep those amendments focused on Obamacare if Republicans narrowly target the budget resolution themselves, but said the strategy would be set by new Minority Leader Chuck Schumer of New York. (Democrats will get another bite at this process in the spring, when Congress considers next year’s budget.)

Once the House and Senate have adopted identical budget resolutions, the committees have to draft the actual repeal bill in each chamber. They’ll have to deliver $2 billion in deficit reduction over a decade set by the resolution, but otherwise are free to write the details of the bill in their committee’s jurisdiction. The major limitation for lawmakers is that they can’t include items that only have an incidental impact on the budget.

Thorny details

But the tougher piece will be agreeing on the details of how much to roll back and when. Republican need to keep at least 50 of 52 of their flock in the Senate on board after Jan. 20, assuming Pence will vote to break ties in their favor and no Democrats defect.

A Republican senator on condition of anonymity said the details of the repeal bill remain very uncertain. Originally, Republicans were planning to simply bring back the bill they put on Obama’s desk last year for his veto.

But that bill was written knowing it wouldn’t become law, and now some Republicans want to make tweaks to soften the blow of repeal.

"Even people who voted for this before are, ‘Wait a minute, wait a minute, we knew that wasn’t going to happen,’" said the senator. "There were no consequences." He said there’s a growing sense among some of his colleagues that they need to have a replacement for Obamacare ready soon "because we’re going to own this."

"I think they’re stuck," Schumer said regarding the prospects of Republicans devising a replacement health-care bill. "They’re going to regret the day they made this their opening issue."

The areas of uncertainty include how long Congress will have to devise a new system -- two years, three years or something else -- and whether to keep some of the revenue and other savings from Obamacare in reserve to pay for a replacement.

"Anything when you get into details is tougher," acknowledged Senator Mike Enzi of Wyoming, the chairman of the Budget Committee.

Split over timing

Republicans like Senator Lamar Alexander of Tennessee -- the chairman of the health committee, one of the two panels that will write the repeal bill -- have publicly urged party members to take their time and work with Democrats on a replacement. But there are also voices that want a repeal and a replacement on a much more urgent schedule.

"I think it should be very short. As short as possible," said Senator Rob Portman of Ohio, of the transition to a new system. "If we don’t I think you’ll see companies pull out of the exchanges, among other things."

Balancing demands for a timely repeal and replacement with senators pressing for flexibility will be difficult, as any group of three Republican senators on either side of the internal debate could stall the process indefinitely.

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