WASHINGTON (Reuters) - President Donald Trump made calls to fellow Republicans in the U.S. Senate on Friday to mobilize support for their party’s healthcare overhaul while acknowledging the legislation is on a “very, very narrow path” to passage.

Five Republican senators have announced they will not support the bill, which is designed to repeal and replace Obamacare, in its current form.

White House officials said on Friday that Trump has been in touch with Senate Majority Leader Mitch McConnell and made calls on Thursday and Friday to other lawmakers.

Trump’s role is expected to become more pronounced in coming days as the vote nears. Senate Republican leaders may rely on the deal-making former businessman to lean on conservative senators who are balking at the bill.

“We’re pleasantly surprised with a lot of the support that’s already come out and I think we’ll continue to work through (it,) in particular the four individuals who have expressed some ideas and concerns,” White House spokesman Sean Spicer told reporters at a White House briefing.

With all Democrats expected to oppose the measure, the Republicans can afford to lose the support of only two of their 52 members if they want to pass the legislation.

After Spicer spoke, Republican Senator Dean Heller became the fifth Republican opponent on Friday, saying he would not support the bill in its current form.

“This bill that’s currently in front of the United States Senate is not the answer,” Heller, a moderate who is up for re-election in 2018, said at a news conference in Las Vegas.

That could add Heller’s name to Trump’s call list. A White House official said the Trump has pushed his team to stay involved and plans to flex his negotiating muscle, the official said.

An outside political group aligned with the White House, America First Policies, said it is planning an advertising campaign targeting Heller for his opposition to the bill.

Healthcare stocks closed down 0.1 percent on Friday, clawing back some losses after the sector dropped sharply late in the session on Heller’s announcement.

The Senate’s 142-page proposal, worked out in secret by a group led by McConnell, aims to deliver on a central Trump campaign promise to undo former President Barack Obama’s signature healthcare law, which has provided coverage to 20 million Americans since it was passed in 2010.

Republicans view the law, formally known as the Affordable Care Act, as a costly government intrusion and say individual insurance markets created by it are collapsing.

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FOUR CONSERVATIVES OPPOSE BILL

On Thursday, four of the Senate’s most conservative members said the new plan failed to rein in the federal government’s role.

Rand Paul, who has rejected the plan along with fellow Republican Senators Ted Cruz, Mike Lee and Ron Johnson, said fundamental problems remained that would leave taxpayers subsidizing health insurance companies.

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Trump, in an interview with Fox News that aired on Friday morning, called the group of conservative lawmakers “four very good people.”

“It’s not that they’re opposed,” he said. “They’d like to get certain changes. And we’ll see if we can take care of that.”

Trump said getting approval would require traveling a “very, very narrow path” but that “I think we’re going to get there.”

“It’s going to be a good bill,” Trump said in a separate Fox News interview to air on Sunday.

For the House of Representatives’ version of healthcare, Trump held regular meetings with representatives at the White House. He celebrated the bill’s narrow passage last month in a Rose Garden event with House Republican leaders.

Trump later criticized the House bill privately as “mean” and this week called for a health plan “with heart.” He indicated the Senate plan met that request.

McConnell said in an interview with Reuters last month that he told Trump early on in the process that he did not need his help but that there may be a role for him later.

The Senate bill maintains much of the structure of the House’s but differs in key ways. It would phase out Obamacare’s expansion of the Medicaid program for the poor more gradually, waiting until after the 2020 presidential election, but would enact deeper cuts starting in 2025. It also would provide more generous tax subsidies than the House bill to help low-income people buy private insurance.