President Donald Trump was just 'having fun' when he told a leading opponent of the GOP leadership's health care bill that he was 'going to come after you' if the bill fails.

The president went to the Capitol Tuesday morning to try to give a final push to the Republican bill to repeal Obamacare – warning GOP lawmakers that their jobs were on the line.

'Many of you came in on the pledge to repeal and replace Obamacare. I honestly think many of you will lose your seats in 2018 if you don't get this done,' he bluntly told the GOP-only gathering, Politico reported.

He was even more direct with Rep. Mark Meadows (R-N.C.), the head over the conservative Freedom Caucus, which met Tuesday as members hashed out whether they would oppose Trump's biggest legislative priority so far.

'I'm gonna come after you, but I know I won't have to, because I know you'll vote 'yes,' ' Trump told Meadows, according to the Washington Post. 'Honestly, a loss is not acceptable, folks.'

Here to deal: President Trump and Tom Price, his Health Secretary, arrives at the Capitol to meet the Republican House Conference

Later Trump told a Republican Congressional Committee fundraiser: 'There are the conservative solutions we campaign on and these are the conservative solutions the American people asked us as, a group, to deliver'

'He has made it very clear that he was having fun with him,' White House press secretary Sean Spicer said when asked about the statement at the daily press briefing.

'Mark Meadows is a longtime early supporter of the president. He had some fun at his expense this morning during the conference meeting,' Spicer explained.

'He continued to express hope that congressman Meadows, who is head of the Freedom Caucus, would continue to see the efforts that have been to make this better.'

Some lawmakers said afterward it seemed Trump was joking, while others complained that Meadows got slapped around.

The president went to the Capitol hours after GOP leaders revealed changes to the legislation in advance of a vote this week.

He told them it wasn't just the nation's health care system that was on the line, but also their own employment.

'I'm asking for your vote on Thursday,' Trump said, according to Politico.

The Freedom caucus, which didn't take a formal position against the bill, nevertheless had the ability to sink it.

Senator Rand Paul (R-Ky.), who clashed with House leaders during the bill's development, told DailyMail.com there were 'at least 30 noes in the House.'

'He told us if we don’t pass this bill on Thursday, it will put everything in jeopardy that he wants to do, his agenda,' Rep. John Duncan (R-Tenn.) told The Hill.

The first-time politician's remarks weren't all gloomy. 'We have a chance to do something fantastic, to do something amazing,' Trump said.

Even Trump's warning to Meadows was made with a smile, Meadows said.

'I'm still a 'no,' ' Meadows said after the meeting, the Post reported. 'I've had no indication that any of my Freedom Caucus colleagues have switched their votes.' He added: ''I didn't take anything he said as threatening anybody's political future.'

Later Trump told a Republican Congressional Committee fundraiser: 'There are the conservative solutions we campaign on and these are the conservative solutions the American people asked us as, a group, to deliver.'

He added: 'I think we're going to have some great surprises. I hope that it's going to all work out.'

A vote is expected Thursday, although the GOP must placate wavering conservatives and moderates. It will be the first major legislative test of the Trump administration in the Republican-controlled Congress.

To help with that task, the leadership announced the details of a 'manager's amendment' incorporating changes – including one intended to satisfy balking New York Republicans.

The GOP must placate wavering conservatives and moderates to get the health care push through to passage.

Beast on the Hill: The President arrives at the Capitol. The move is a bid to seal the deal on repealing and replacing Obamacare

Selling hard: Paul Ryan, the House Speaker, is trying to do everything in his power to get the health reform bill through on Thursday

According to a whip list in The Hill, released before the latest changes got released, 17 Republicans had indicated they were against the effort.

The Republicans can only afford to lose 21, assuming all of the Democrats vote against the plan to repeal President Obama's signature health proposal. A different set of problems await the bill in the Senate, where several GOP lawmakers have expressed concern.

Trump tried to fire up House conservatives, who are homing in on specifics like Medicaid reimbursement rates.

'We're gonna negotiate and it's going to go to the Senate and back and forth. The end result is going to be wonderful, and it's going to work great,' Trump said at a campaign rally Monday night.'

Art of the deal: The president has described the process of dealing with healthcare as a 'big, fat, beautiful negotiation'

Entourage: The president brought a series of senior figures to Capitol Hill - including Kellyanne Conway, his senior adviser, and (right) Gary Cohn, director of the National Economic Council

The Republican leadership proposed a series of amendments that marked major legislative changes, but it was not immediately clear whether they would help win more Republican support amid solid opposition from Democrats.

A leading conservative voice in the House, Representative Jim Jordan of Ohio, is still opposed to the legislation even with the proposed changes, according to an aide.

The administration and House leadership can only afford to lose about 20 votes from Republican ranks. They need to shore up support from moderate Republicans who fear the bill dismantling President Barack Obama's signature Affordable Care Act will hurt millions of Americans enrolled in the program.

However, Trump and Republican leaders must also appeal to hard-right conservatives who believe the original bill did not go far enough in repealing the law, prompting some to dub it 'Obamacare Lite.'

According to Republican sources who asked not to be identified, House leaders will propose an approximately $85 billion fund for tax credits to help people aged 50-64 get health insurance.

In an unusual move, the House proposed providing the Senate flexibility to offer more help to that age group, which may need a larger tax credit to help cover their healthcare costs - a move aimed at winning over more moderate Republicans. It did not specify how the Senate should do so.

Conservatives have opposed refundable tax credits, calling them another entitlement program.

One amendment would dismantle most of Obamacare's taxes one year earlier than initially proposed, in 2017 instead of 2018. That includes both the individual mandate that requires everyone to purchase health insurance or else pay a penalty, and the requirement that employers of a certain size provide coverage.

The new language also addresses Medicaid, the federally backed healthcare program for the poor and disabled that is one of the most contentious aspects of the bill.

To appease conservatives, states would have the option of implementing work requirements for able-bodied adults without children or dependents. However, even the Heritage Foundation, a powerful conservative group, has opposed such a provision.

In addition, states could decide whether to take per capita allotments for their Medicaid programs or block grants for certain populations. Both would drastically reduce federal Medicaid funding from current levels.

Republican leaders hope to move the legislation to the House floor for debate as early as Thursday.

At a rally in Louisville, Kentucky, on Monday night, Trump said he wanted to add a provision to the bill that aims to lower prescription drug costs through a 'competitive bidding process.'

'We're trying to add it to this bill and if we can't, we'll have it right after,' he said. During the presidential campaign, Trump called for allowing Medicare to negotiate with pharmaceutical companies, something the law currently prohibits.

The Congressional Budget Office (CBO) analysis of the original House Republican bill a week ago severely damaged its prospects. It said 14 million people would lose health coverage under the measure over the next year and 24 million over the next decade.

The CBO is expected to update its analysis of the impact of the legislation to take into account the latest changes being proposed.

Under the retooled legislation, the rollback of Obamacare's Medicaid expansion, which provided states enhanced federal funding for new enrollees, would be slowed.

More than 30 states, including about a dozen with Republican governors, chose to expand their Medicaid programs under Obamacare. Several Republican governors and key senators and House members have expressed concern over abruptly cutting federal Medicaid funding and therefore taking insurance away from millions of people.

Republican leaders are now proposing that many of those who gained coverage under the expansion could keep it. The federal government would maintain the higher funding levels for those up to 133 percent of the federal poverty level. Obamacare expanded coverage to those making incomes up to 138 percent.

Those beneficiaries could keep their coverage until they 'cycle off' the program, possibly because they would eventually make enough money to purchase private insurance or obtain it through an employer.

Another amendment would allocate more money for healthcare costs for the disabled and elderly on Medicaid. The unusual mix of amendments to Medicaid reflects leadership's attempt to assuage concerns from both staunch conservatives and moderates.

Democrats oppose the Republicans' plan, which they say would throw millions off health insurance and hurt the elderly, poor, and working families while giving tax cuts to the wealthy.

Democrats as well as hospitals and insurers have urged Republicans to consider how their plan would affect access to healthcare for the 20 million people insured by Obamacare.