(Recasts with White House efforts to win support; adds Ryan comments)
By Susan Cornwell and David Morgan
WASHINGTON, March 15 (Reuters) - President Donald Trump was working late on Wednesday to shore up support among skeptical fellow Republicans in Congress for a plan to dismantle much of Obamacare, as signs emerged that some conservatives skeptical of the proposal were now coming around.
Trump was expected to try to drum up support among voters for the plan at a rally in Nashville, Tennessee, amid worries triggered by a Congressional Budget Office projection that millions of Americans would lose health insurance coverage under the plan.
"We're obviously in talks with Speaker Ryan, the entire leadership team over there ... to get the best outcome based on feedback from members," White House spokesman Sean Spicer told reporters during a briefing.
Paul Ryan, the top House of Representatives Republican, continued to champion the legislation he unveiled last week, saying on cable news that he was open to making "improvements and refinements," but adding, "The major components are staying intact."
Some Republicans indicated they were changing their minds after initially questioning the legislation on the grounds that it too closely resembled Obamacare, the signature domestic policy achievement of former President Barack Obama.
Key conservative lawmakers said on Wednesday they were close to embracing Ryan's plan. This came after the White House signaled flexibility on a government health insurance program. Specifically, conservatives want Obamacare's expansion of the Medicaid program for the poor to end sooner than proposed by the Ryan plan, and want to introduce Medicaid work requirements for able-bodied adults without children.
Speaking on CNN, Ryan mentioned Medicaid, but gave no details of the negotiations. State governments run Medicaid with reimbursements from the federal government. Obamacare expanded it to reach more people and increased funding for it.
"Where we can improve the bill ... that’s exactly what we’re doing," Ryan said. “Medicaid flexibility is a good example. Giving states better chances at more flexibility.”
Vice President Mike Pence earlier in the day advocated for the plan behind closed doors with the Republican Study Committee, a large group of House conservatives.
Republican Representative Phil Roe said after the Pence meeting that the bill probably would be changed to move up by one year, to 2019, the end of the Medicaid expansion.
Obamacare enabled about 20 million previously uninsured Americans to obtain medical insurance, about half through the expansion.
The conservative group's members are "very close to signing off" on the legislation, its leader, Representative Mark Walker, told reporters.
Republicans control both Congress and the White House for the first time in a decade. But the bill, the Republicans' first major piece of legislation under Trump, has not been an easy sell to conservatives.
Senate Republicans have also voiced rising unease.
"As written, the House bill would not pass the Senate. But I believe we can fix it," Senator Ted Cruz told reporters.
Republican Senator Lindsey Graham told NBC's "Today" show, "It is mortally wounded."
The conservative advocacy group FreedomWorks held a rally amid snow flurries and a frigid wind outside the Capitol where several House and Senate Republicans including Cruz and Senator Rand Paul voiced dissatisfaction with the bill.
Afterward, Paul told reporters, "The White House has been much more open to negotiation on this" than House leaders. Trump on Monday promised "a big, fat, beautiful negotiation" over the plan.
The CBO, a nonpartisan congressional agency, forecast on Monday the plan would increase the number of Americans without health insurance by 24 million by 2026, while cutting $337 billion off federal budget deficits over the same period.
The legislation guts key provisions of the 2010 Affordable Care Act.
Many conservatives have called the bill's age-based tax credits to help people buy private insurance on the open market an unwise government entitlement.
Two House committees last week approved the bill's provisions with no changes. The Budget Committee on Thursday will try to unify the plan into a single bill for consideration on the House floor. Republicans cannot afford to lose more than three from their ranks on the committee for it to pass. Three committee Republicans are members of the hardline conservative House Freedom Caucus.
Shares of hospitals traded broadly higher, with Community Health Systems rising 4.4 percent. Health insurer shares also gained, with Anthem up 2.4 percent after the insurer also backed its full-year profit forecast.
The U.S. Department of Health and Human Services released data showing enrollment in the individual insurance plans created under Obamacare have declined to 12.2 million Americans.
As of the end of January, enrollment in these individual insurance plans was down by about 500,000 people from 2016, it said. It is about 1.6 million people short of Obama's goal for 2017 sign-ups, the government said.
(Additional reporting by David Morgan, Lewis Krauskopf, Caroline Humer, Ayesha Rascoe; Writing by Will Dunham and Lisa Lambert; Editing by Kevin Drawbaugh and Leslie Adler)