Washington (CNN) Three months ago, just before Donald Trump took office, about half of Americans said it was very likely that the new President, armed with a Republican majority in both houses of Congress, would repeal and replace the law known as Obamacare.

Now, after multiple unsuccessful efforts to fulfill that campaign pledge, a new CNN/ORC poll finds just 20% say it's very likely the President and Republicans in Congress will fulfill that promise.

The poll findings come as Republicans in the House have said they won't bring a third iteration of a repeal-and-replace bill to the floor this week, meaning it certainly won't happen during Trump's first 100 days in office. Repealing and replacing Obamacare was part of the Contract with American Voters that Trump unveiled in Gettysburg, Pennsylvania, during the campaign, outlining the actions he would take in his first 100 days as president.

The 30-point drop in the share seeing repeal and replace as "very likely" means even the Republican laity isn't so sure a deal will get done. Just 29% of Republicans and Republican-leaning independents say it's very likely, down from 67% who thought Trump would get it done in January. Democrats and Democratic-leaners have grown more skeptical as well, with 10% in that group saying it's very likely now, down from 36% in January. Obamacare itself continues to draw mixed reviews, according to the poll, with 47% in favor of it and 48% opposed.

Congress, however, is decidedly unpopular. The poll finds 24% approve of the way Congress is handling its job, 74% disapprove. That's a bit higher than the 20% approval rating Congress held in mid-January, but below the 35% approval rating the Democratic-controlled body held in 2009 as the 100-day mark of President Barack Obama's presidency approached.

The majority leaders in each chamber, House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell, both have favorability ratings that are significantly net-negative. McConnell started out the year in negative territory and has actually seen his favorability rise a bit: 20% had a favorable view in January, 27% do now. That shift is almost entirely among Republicans. Back in January, 33% of Republicans had a favorable take, while 51% do now, perhaps fueled by McConnell's key role in supporting Trump's biggest accomplishment as president: the confirmation of Neil Gorsuch to the Supreme Court.

Ryan's numbers, however, have flipped in the last few months, and he's lost ground across party lines. He kicked off the year with a 46% favorable, 35% unfavorable rating, and now stands at 38% favorable to 48% unfavorable. His favorable numbers have dipped 7 points, to 66%, among Republicans and 12 points, to 16%, among Democrats.

Taking an early look at next year's congressional elections, a generic ballot yields a Democratic advantage, with 50% saying they'd vote for the Democratic candidate in their district and 41% the Republican candidate if the election were held today. A lead that large, this far out, is not necessarily predictive, however -- although it approaches the edge Democrats held early on in the 2006 election cycle when they won control of the House, it is also similar to their advantage early on in the 2010 cycle, which ended with a Republican takeover of the chamber.

Trump could prove to be a drag on GOP candidates for the House, with 55% saying they'd be more likely to vote for a candidate who opposes Trump than one who supports him; 41% prefer a Trump supporter. That divide is similar to the preference for opposition to Obama ahead of the 2014 elections and George W. Bush before the 2006 contests.

The effects of the effort to repeal Obamacare, however, appear more mixed. Asked whether they'd be more or less likely to support their own member of Congress should they vote to repeal the ACA, 36% said they'd be more likely to back a repeal-supporting member of Congress and 32% less likely, but fully 30% said whether their congressperson voted to repeal wouldn't matter to their 2018 ballot choice.

And looking at the Democrats who were vying for the White House at this time last year, Vermont Sen. Bernie Sanders remains broadly popular, with 59% holding a favorable view and 35% unfavorable, virtually unchanged since the end of the Democratic nomination process, while Hillary Clinton continues to garner mostly unfavorable views. In the new poll, 43% have a positive take on Clinton, 54% a negative one. That's a slight shift upward compared with her post-election mark of 40% favorable, but remains well below the majority favorable ratings she consistently held before she re-entered the political limelight in 2015. Clinton's numbers are similar to those for Trump (45% have a favorable view of the president, 53% unfavorable).

And Sanders stands as the more popular of the two among Democrats and Democratic leaners -- 82% have a favorable take on the Vermont senator, 68% view Clinton favorably. That difference comes largely from independents who lean Democratic, a critical group for Sanders' success in last year's primaries and caucuses. Among self-identified Democrats alone, 83% have a favorable take on Sanders, 81% on Clinton.

The CNN/ORC poll was conducted by telephone April 22-25 among a random national sample of 1,009 adults. Results for the full sample have a margin of sampling error of plus or minus three percentage points. It is larger for subgroups.