US President Donald Trump acknowledged that a lack of support from four Senate Republicans leaves the party's healthcare overhaul on a "very, very narrow path" to win passage, but signaled a willingness to work with them to make changes. "It's not that they're opposed. They'd like to get certain changes. And we'll see if we can take care of that," Trump said in an interview with Fox News that aired on Friday, calling the group of conservative lawmakers "four very good people." Trump earlier indicated changes may be in store for the proposal unveiled by Senate Republicans on Thursday to replace former President Barack Obama's signature healthcare law. The plan would scale back aid to the poor and kill a tax on the wealthy. "I am very supportive of the Senate #Healthcarebill. Look forward to making it really special!" Trump wrote on Twitter on Thursday. The Republican bill aims to deliver on one of Trump's central campaign promises to "repeal and replace" the 2010 law passed under Obama that expanded coverage to millions of Americans. Its fate remained uncertain after the four lawmakers refused to back the current Senate plan, leaving Republicans short of the votes needed for passage. Democrats are united in opposition to the proposal, which was worked out in secret by a group led Senate Majority Leader Mitch McConnell. Republicans view Obama's Affordable Care Act as a costly government intrusion into the private marketplace. The four Republican holdouts, among the Senate's most conservative members, said the plan did not go far enough in scaling back the federal government's role, highlighting Republicans' struggle to craft legislation to revamp a sector that accounts for one-sixth of the world's largest economy. Rand Paul of Kentucky, who has rejected the plan along with fellow Republican Senators Ted Cruz of Texas, Mike Lee of Utah and Ron Johnson of Wisconsin, said fundamental problems still remain that would leave taxpayers subsidizing health insurance companies. "I want the bill to look more like a repeal bill," Paul told MSNBC on Friday. The Senate measure maintains much of the structure of a House bill passed in May but differs in several key ways. If it passes, it would have to be reconciled with the House version before Trump could sign it into law. While Republicans control both chambers of Congress and the White House, the party's efforts to unwind Obamacare has been dogged by internal conflicts between moderate and hard-line members of the party. Trump publicly celebrated the House bill's passage, only to criticize it in private as "mean." This week he called for a health plan "with heart." Democrats have sharply criticized both versions as a giveaway to the wealthy that would leave millions without health insurance. On Thursday, Obama weighed in on Facebook, writing: "If there's a chance you might get sick, get old, or start a family – this bill will do you harm." The Senate bill's real-world impact is not yet known, but the nonpartisan Congressional Budget Office is expected to provide an estimate early next week. The CBO had found that the House bill would kick 23 million Americans off their health plans, making it unpopular with the public. Fewer than one in three Americans supports it, according to Reuters/Ipsos polling. — Reuters