With the effort to repeal and replace the health care law of Trump's predecessor floundering in Congress, the Senate prepared to vote Tuesday on whether to begin debate on the latest Republican plan.
Several measures have been considered but then collapsed in recent weeks. The latest is a bid to dismantle the 2010 Affordable Care Act, but delay the actual implementation of the repeal to allow time for a viable replacement to be crafted.
Senate Republican leaders acknowledge they do not know whether there is sufficient support to open debate on the new plan, a sign of Republican division about the impact such reforms might have on millions of American families.
With less than three weeks before the Senate is to leave Washington for its already-delayed summer recess, Trump took to his bully pulpit and demanded his party get in line.
"Any senator that votes against starting debate is telling America that you are fine with the Obamacare nightmare," Trump said at the White House, where several "victims" of Obamacare stood as a backdrop to his remarks.
"Obamacare is death," Trump added. "It's gone. And now it's up to us to get great health care for the American people."
Trump has repeatedly grilled fellow Republicans for not following through on their -- and his -- campaign pledge to repeal and replace Obamacare, something he said he aimed to do immediately once in office in January.
"Over and over again they said repeal and replace. And for Senate Republicans, this is their chance to keep their promise."
Republicans hold 52 of the Senate's 100 seats. With all Democrats opposed, Trump can afford just two defectors.
But with Senator John McCain convalescing in Arizona following a brain cancer diagnosis, that magic number is down to one.
As of last week, three Republican holdouts said they will vote no on Tuesday's so-called motion to proceed, which opens debate on the legislation.
Trump went to one of their home states Monday, where he was to personally lobby Senator Shelley Moore Capito as the two attended a Boy Scouts convention in Beaver, West Virginia.
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'Repercussions'
Several other Republicans have also expressed concerns, but have not announced how they will vote.
"I think until the vote is actually on the floor of the Senate, some people may not tell you what they're actually going to do," Senate Republican John Barrasso told CBS talk show "Face the Nation" on Sunday.
Once the repeal-only bill is on the floor, it could be amended "in various ways," Barrasso said, including changing it to a repeal-and-replace bill.
Forecasts by the non-partisan Congressional Budget Office on various health reform bills have predicted that millions of Americans would lose health care if the measures become law.
In the case of a bill that repeals Obamacare and provides no replacement, 32 million more people would be uninsured by 2026 as compared to current law, CBO forecast.
Some Republicans have expressed concern with how legislation would impact Medicaid, the health insurance program for the poor and the disabled.
The latest repeal-and-replace bill would roll back an expansion of Medicaid and slash its federal funding.
It would also end the mandate that most individuals have health insurance, and allow states to let insurance companies offer bare-bones plans not allowed under current law.
Despite the concerns voiced by some Republicans -- and several outside groups -- Trump issued an ominous threat.
"If Republicans don't Repeal and Replace the disastrous ObamaCare, the repercussions will be far greater than any of them understand!" he tweeted.
It was not clear if Trump was referring to the prospect that failure to pass reform will lead to election challenges against GOP incumbents, or hurt American families.
Majority Leader Mitch McConnell meanwhile opened the Senate Monday by urging his colleagues to vote to "kick off a robust debate" in which senators can introduce amendments to the bill.
