Washington - Message to President Donald Trump and congressional Republicans: Stop trying to scuttle the Obama health care law, and start trying to make it more effective.That's the resounding word from a national poll released on Friday by the non-partisan Kaiser Family Foundation. The survey was taken following last month's Senate derailment of the GOP drive to supplant much of President Barack Obama's statute with a diminished federal role in health care.Around 4 in 5 want the Trump administration to take actions that help Obama's law function properly, rather than trying to undermine it. Trump has suggested steps like halting subsidies to insurers who reduce out-of-pockets health costs for millions of consumers. His administration has discussed other moves like curbing outreach programmes that persuade people to buy coverage and not enforcing the tax penalty the statute imposes on those who remain uninsured.Just 3 in 10 want Trump and Republicans to continue their drive to repeal and replace the statute. Most prefer that they instead move to shore up the law's marketplaces, which are seeing rising premiums and in some areas few insurers willing to sell policies.Flying in the face of that, hard-line conservatives launched an uphill bid on Friday to force a fresh House vote to revoke Obama's law without an immediate replacement. The House Freedom Caucus filed a petition to force a vote if it is signed by 218 lawmakers, which seems unlikely because of GOP divisions and Democratic opposition.Ominously for the GOP, 6 in 10 say Trump and congressional Republicans are responsible for any upcoming health care problems since they control government. That could be a bad sign for Republicans as they prepare to defend their House and Senate majorities in the 2018 elections.And by nearly 2-to-1, most say it's good that the Senate rejected the GOP repeal-and-replace bill last month.Trump has been publicly browbeating Senate Majority Leader Mitch McConnell, R-Ky., to continue trying to pass legislation tearing down Obama's 2010 overhaul. After using Twitter to blame McConnell for last month's Senate failure despite years of GOP vows to repeal it, Trump suggested on Thursday that McConnell should perhaps step aside if he can't push that and other legislation through his chamber.Republicans still supportOn three separate attempts in late July, McConnell fell short of the 50 GOP votes he needed to pass legislation scrapping Obama's law. With a 52-48 GOP majority and Vice President Mike Pence available to cast a tie-breaking vote, McConnell has said he's moving onto other matters unless "people can show me 50 votes for anything that would make progress."With the Kaiser survey consistently showing clear overall public support for retaining Obama's law, the numbers help explain why some centrist Republicans who rely on moderate voters' support opposed repeal or backed it only after winning some concessions.Strikingly, while large majorities of Democrats and independents back efforts to sustain the statute, even Republicans and Trump supporters lean toward saying the administration should try making the law work, not take steps to hinder it.But in other instances, Republicans and Trump supporters part company with Democrats and independents and strongly back the president's views. For a White House that often seems more concerned with cementing support from Trump's loyalists than embracing the political centre, that might help explain the president's persistence on the issue.For example, 6 in 10 Republicans and Trump backers want the GOP to continue its repeal and replace drive in Congress. And around two-thirds from those groups want Trump to stop enforcing the tax penalty Obama's law levies on people who don't buy coverage. Analysts say that would roil insurance markets because fewer healthy people would buy policies, leaving them with greater proportions of expensive, seriously ill customers.Trump has frequently tried pressuring Democrats to negotiate on health care by threatening to halt federal subsidies to insurers. While around 6 in 10 overall say Trump should not use such disruptive tactics, a majority of Republicans back that approach.The companies use the money to trim out-of-pocket costs for deductibles and co-payments for around 7 million low- and middle-income people. Since insurers are legally required to reduce those costs, they say blocking the subsidies would force them to increase premiums for millions who buy private insurance, including those whose expenses aren't being reduced.The poll found that 52% have a positive view of Obama's law, a 9 percentage point increase since Trump was elected last November.The Kaiser Health Tracking Poll was conducted Aug. 1-6 and involved random calls to the cellphones and landlines of 1 211 adults. The margin of sampling error for all respondents is plus or minus 3 percentage points.