WASHINGTON -- Lecturing fellow Republicans, President Donald Trump summoned GOP senators to the White House Wednesday and told them face-to-face they must not leave town for their August recess without sending him an "Obamacare" repeal bill to sign. Senators responded by vowing to revive legislative efforts left for dead twice already this week.

Success was far from assured, but Trump declared "I'm ready to act," putting the responsibility on Republican lawmakers, not himself. During last year's presidential campaign he had declared repeatedly it would be "so easy" to get rid of the Obama law.

The developments Wednesday came just a day after the latest GOP health care plan collapsed in the Senate, leading Trump himself to say it was time to simply let President Barack Obama's health care law fail. Majority Leader Mitch McConnell had indicated he was prepared to stick a fork in the Republican bill and move on to other issues including overhauling the tax code.

But in an apparent change of heart, in keeping with his erratic engagement on the issue, Trump pressured McConnell to delay the key vote until next week, and he invited Republican senators to the White House for lunch.

There, with the cameras rolling in the State Dining Room, Trump spoke at length as he cajoled, scolded and issued veiled threats to his fellow Republicans, all aimed at wringing a health care bill out of a divided caucus that's been unable to produce one so far.

"For seven years you promised the American people that you would repeal Obamacare. People are hurting. Inaction is not an option and frankly I don't think we should leave town unless we have a health insurance plan," he said.

Seated next to Nevada Sen. Dean Heller, who is vulnerable in next year's midterm elections, Trump remarked: "He wants to remain a senator, doesn't he?" as Heller gave a strained grin.

It was not clear that the White House lunch would change the calculus in the Senate, where McConnell has failed repeatedly to come up with a bill that can satisfy both conservatives and moderates in his Republican conference. Two different versions of repeal-and-replace legislation fell short of votes before coming to the floor, pushing him to announce Monday night that he would retreat to a repeal-only bill that had passed Congress when Obama was in office.

But that bill, too, died a premature death as three GOP senators announced their opposition on Tuesday, one more than McConnell can lose in the closely divided Senate. Further complicating that approach, the Congressional Budget Office released an analysis Wednesday reaffirming its earlier findings that the repeal-only bill would mean 32 million additional uninsured people over a decade and average premiums doubling.

And a new AP-NORC poll found that Americans overwhelmingly want lawmakers of both parties to work out health care changes, with only 13 per cent supporting Republican moves to repeal the Obama law absent a replacement.

At the White House lunch, the discussion was not simply about repealing "Obamacare" but also how to replace it as Republicans said that after seven years of promises, they could not let their efforts die without one last fight.

"This is more than just a health care debate," said Sen. Pat Roberts of Kansas as he left the meeting. "It really means, can we come together as a conference, can we come together as a Republican Party, can we come together on a signature piece of legislation we've talked about for seven years.

"If we don't, I think it's pretty clear the political consequences are staring us right in the face," Roberts added.

The administration scheduled a late-night meeting at the Capitol with Vice-President Mike Pence and others for undecided senators to air their concerns.

McConnell announced that the Senate would vote next week to open debate, and "I have every expectation that we will be able to get on the bill" -- although no one seemed quite sure what bill it will be.

Sen. Lisa Murkowski of Alaska, who on Tuesday announced she would vote "no" on the "motion to proceed" to the repeal-only bill, demurred when asked after Wednesday's lunch whether she remains "no," telling reporters: "We don't know what the motion to proceed is for all certainty. ... I think that there's going to be a lot more discussion before there's a motion to proceed."

Trump's sudden re-resolve to get "Obamacare" repeal-and-replace passed came after he's been on all sides of the issue in a whiplash-inducing series of remarks over recent days and weeks, supporting repeal and replace, straight repeal, and finally doing nothing so "we'll just let Obamacare fail," as he declared on Tuesday.

He's also failed to use his "bully pulpit" to sell the GOP legislation to the public, something he promised senators he would remedy, according to Roberts.

Yet for all the determined rhetoric Wednesday, the basic divisions haven't changed in the Senate, where conservatives like Rand Paul of Kentucky want legislation that fully repeals the Obama law while moderates like Susan Collins of Maine want something incompatible with that, a more generous bill that provides for Americans including those who gained Medicaid coverage under the Affordable Care Act.

"We don't have any delusions about the fact that this is going to be very hard," said Sen. John Thune of South Dakota, the No. 3 Senate Republican. "And we still have members who are not there yet."

------

Associated Press writers Ken Thomas, Catherine Lucey, Stephen Ohlemacher, Richard Lardner, Andrew Taylor, Matthew Daly and Mary Clare Jalonick contributed to this report.