(Reuters) - U.S. President Donald Trump used his barnstorming strategy on Wednesday to try to build momentum for his first legislative initiative, a healthcare overhaul, by holding a massive rally in Nashville, Tennessee, reminiscent of his campaign events. Back on Capitol Hill, Republican leaders negotiated behind closed doors, held media conferences and gave cable-news interviews as they tried to push forward their plan to dismantle the Affordable Care Act, commonly called Obamacare. After Republican House Speaker Paul Ryan unveiled the new plan last week, fault lines appeared within the party as some conservatives said it did not go far enough and others rejected it entirely.  Trump used campaign-like language in his Wednesday night speech, pledging “to repeal and replace horrible, disastrous Obamacare.” Speaking to reporters aboard presidential plane Air Force One after the rally, Trump expressed optimism about his plan’s chances in Congress.  “We’re going to come up with something. We always do,” he said. Republicans control both Congress and the White House for the first time in a decade, but the overhaul still faces political battles to be fought by a president new to governing. White House spokesman Sean Spicer told reporters before the rally the Trump administration had been in talks with Ryan and congressional leaders and was flooding the media with interviews with administration officials to help advance the plan. Ryan, the top Republican in the House of Representatives, also continued to champion the legislation, saying on cable news he was open to making “improvements and refinements,” but also adding “the major components are staying intact.” He told a news conference later in the evening the House would hold votes on repealing and replacing Obamacare but refused to provide a timetable. Two House committees approved the bill’s provisions with no changes last week. The Budget Committee will try on Thursday 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. Signs emerged on Wednesday that the White House was winning over reluctant conservatives who initially questioned the legislation on the grounds that it too closely resembled Obamacare, the signature domestic policy achievement of former President Barack Obama. The administration indicated it was open to revisiting the plan’s treatment of Medicaid, the government health insurance program for the poor, during a meeting with a conservative wing of the party. Specifically, conservatives want Obamacare’s expansion of Medicaid to end sooner than proposed in the Ryan plan, and want to introduce Medicaid work requirements for able-bodied adults without children. State governments run Medicaid with reimbursements from the federal government. Obamacare expanded its eligibility and increased funding for it, which enabled about 10 million previously uninsured Americans to obtain medical insurance.  Vice President Mike Pence advocated for the plan earlier on Wednesday behind closed doors with the Republican Study Committee, a large group of House conservatives. Republican Representative Phil Roe said after the Pence meeting the bill would probably be changed to move up the end of the Medicaid expansion by one year, to 2019. The conservative group’s members were “very close to signing off” on the legislation, its leader, Representative Mark Walker, told reporters. Speaking on CNN, Ryan mentioned “giving states better chances at more flexibility with Medicaid,” but provided no details. Just as the party’s conservatives began expressing optimism about the proposal’s fortunes, Republican moderates raised concerns that tax credits currently in the bill intended to help people buy health insurance were not sufficient. Representative Charlie Dent, following a meeting of moderate Republicans with Pence, told reporters that speeding up the termination of the Medicaid expansion was a “non-starter.” 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. Paul later told reporters: “The White House has been much more open to negotiation on this” than House leaders.  A libertarian, Paul posted an op-ed on the Breitbart News website later on Wednesday calling Ryan’s plan “Obamacare Lite” and suggesting smashing it to “smithereens.” The U.S. Department of Health and Human Services released data showing enrollment in the individual insurance plans created under Obamacare has declined to 12.2 million Americans. Enrollment in these individual insurance plans was down by about 500,000 people from 2016 by the end of January, it said. It is about 1.6 million people short of Obama’s goal for 2017 sign-ups, the government said. 