Public opposition to the new health care law has eased in the past month, enough to help level off Barack Obama's falling popularity - but not to turn it around.

Fifty-five percent of Americans in a new ABC News/Washington Post poll disapprove of the president's job performance overall, unchanged from last month's reading as the worst of his career. Forty-three percent approve, a scant percentage point from 42 percent in November.

See PDF with full results, charts and tables here.

Better for the president is an easing of opposition to the Affordable Care Act, with attitudes back to a close division on the law; 46 percent of Americans support it, with 49 percent opposed. Opposition is down from a record 57 percent last month amid the new system's troubled rollout.

The ACA's impact to date on Americans' perceptions of the quality of their health care, coverage and costs is less negative than many anticipated when it was signed into law. But while 37 percent in 2010 expected the law to improve the health care system overall, just 19 percent now say it's actually done so. And far more, 47 percent, say it's made things worse.

Many Republicans reportedly plan to make criticism of the ACA a centerpiece of their midterm election campaigns, and the approach shows promise. 2014 election preferences have tightened essentially to a dead heat, with 47 percent of registered voters now supporting the Democratic candidate in their congressional district vs. 45 percent for the Republican. That compares with an 8-point Democratic lead in October, just after the unpopular, GOP-inspired partial government shutdown and just before the HealthCare.gov meltdown.

Moreover, among registered voters who oppose the health care law - in general, no fans of the Obama administration - midterm preferences stand at 64-26 percent in favor of GOP candidates.

POLITICS AND TRUST - Other results mark both Obama's difficult year and the way in which controversy over the health care law's implementation largely has erased what had been a Democratic advantage after the government shutdown. Most tellingly, Americans by 48-40 percent now trust congressional Republicans over Obama to pick the right balance of budget cuts and spending on needed programs. That's reversed from an 11-point Obama lead on the question in late October, and it's the first significant GOP lead on the issue in data since early 2011.

The poll, produced for ABC by Langer Research Associates, finds that changes in this view are striking in some particular groups. Preference for the GOP approach over Obama's in handling budget cuts vs. maintaining needed programs has risen since the shutdown by 18 points among independents and also by 18 points among adults younger than age 30, customarily a strong Obama group but one in which he lost ground sharply last month.

Trust for the GOP on funding issues also has risen since the shutdown by 16 points among women and by 14 points among adults with lower and lower-middle incomes, two other consistently better groups for Obama, and therefore surely a cause of concern to Democrats. (Separately, Americans by 50-35 percent say they support last week's budget deal financing the government through September 2015; the rest have no opinion.)

More broadly, Americans divide evenly, 41-41 percent, on whom they trust more to handle the nation's main problems, Obama or the Republicans in Congress. A year ago, still celebrating his post re-election boost, Obama held a 15-point advantage on this measure. And on another key issue in the midterms, the public also divides evenly on which political party has better ideas about "the right size and role of the federal government."

Then there's the economy, a persistent source of political discontent. While 59 percent of Americans say the economy has begun to recover, a new high in data since 2009, just 15 percent see the recovery as a strong one. Indeed 79 percent say that from their perspective the country still is in a recession. Fifty-five percent disapprove of how Obama's handling the economy. And, potentially further aiding their midterm prospects, the Republicans in Congress score 45-41 percent vs. Obama in trust to handle the economy, compared with 38-44 percent last month - up a significant 7 points for the GOP.

Another result shows the extent to which Obama has continued to benefit from his predecessor's poorly rated economic performance: Nearly five years after he left office, more Americans still blame George W. Bush more than Obama for current economic problems, 50 vs. 38 percent. That said, the view is a highly partisan one - and blame for Obama is at a new high, up 9 points since the question first was asked in early 2012.

MORE POLITICS - Among other results on the state of play politically as 2013 draws to its close:

2013 was the year of the independent - again. On average this year more Americans in ABC/Post polls have identified themselves as independents (37 percent) than either as Democrats or Republicans (32 and 23 percent, respectively). It's the fifth year in a row this has happened, far surpassing a two-year streak in 1994-5, in ABC/Post polling since 1981. The predominance of political independents marks dissatisfaction with the two main parties and can lead to volatility in election contests.

Obama, for his part, ends the year on a decidedly sour note, with his job approval rating below his yearlong average of 48 percent; among groups, he's at a career low in approval among whites, at just 30 percent, with 68 percent disapproving. Further, his five-year average, 51 percent, is the lowest on record in ABC/Post and Gallup polls before them back to Harry S. Truman, although similar to the five-year averages of Bill Clinton and Richard Nixon (both 53 percent).

Another notable element is the vast partisan and ideological polarization that surrounds Obama. On average in the past five years his approval rating has been 68 points higher among Democrats than Republicans and 50 points higher among liberals than conservatives - far surpassing comparable figures for Ronald Reagan, Clinton and George W. Bush.

As weak as Obama's current 43 percent job approval rating may be, it shines compared with that of the Congress overall (16 percent), the Republicans in Congress (24 percent) or the Democrats there (34 percent). At the same time, "strong" disapproval of the Congress has eased from 70 percent at the time of the shutdown to 59 percent now. Congress' approval rating has averaged 17 percent this year, vs. a long-term average, in available data back to 1974, of 37 percent.

Obama holds a modest advantage, albeit much diminished, in trust over the GOP to do a better job "protecting the middle class." That now stands at 46-40 percent; Obama's 6-point edge has contracted dramatically from 26 points on this measure, 58-32 percent, a year ago.

Still, in a stanching of his losses, the public's sense that the president "understands the problems of people like you" has inched back to a majority, 52 percent, from 47 percent last month. And 50 percent now call him honest and trustworthy; this was a career-low 47 percent in November.

OBAMACARE - Criticism of the health care law and its rollout remains substantial. Sixty-four percent say that from what they've heard the federal government's sign-up website still is not working as it should. Sixty-two percent disapprove of Obama's handling of the law's implementation, essentially unchanged from last month. Fifty-five percent still call the website's failure "a sign of broader problems in implementing the health care law." And 60 percent say the law's individual mandate should be delayed, although, in one of the poll's single biggest one-month changes, that's down from 71 percent in November.

There are particular groups in which the rollout has prompted unsettled responses to the health care law. Last month opposition jumped by 16 points among adults under age 30. Now opposition among under-30s has turned the other way, dropping by 18 points. Opposition also has eased by 17 points among political conservatives, though it's still a substantial 64 percent in this group.

Opposition to the ACA also has eased by 13 points among men, and men are 15 points less apt this month than last to say the law's individual mandate - long its least popular element - should be delayed. Support for delaying the requirement that nearly all Americans get insurance or pay a fine also has subsided in two of the law's best support groups - among nonwhites, with a 22-point drop in support for delaying the mandate; and among Democrats, with an 18-point decline.

ACA IMPACTS - Additional results on the health care law indicate that Americans are finding it less personally damaging than many had anticipated. But it's also seen as less beneficial to the system overall than many expected.

Specifically, when Obama signed the law in March 2010, 44 percent of Americans thought it would worsen the quality of their own health care; today far fewer, 25 percent say it's in fact done so. Forty-two percent thought the law would worsen their insurance coverage; 32 percent say that's actually happened. And 55 percent thought it would increase their costs; 47 percent now say it's had that effect.

Indeed, Americans overall report less of any impact on their own care, quality and costs than they'd anticipated. That said, the negatives, even if less bad than expected, are still serious, especially the perceived impact on personal costs.

In terms of the system more broadly, 60 percent thought the law would raise the nation's overall costs of health care, and an identical number now say it's done so. And in perhaps the most challenging result for the administration, as noted above, only 19 percent say the law so far has improved the health care system overall, vs. 37 percent who thought it would - and compared with 47 percent who think it's made things worse. That's the kind of result the GOP looks primed to highlight from here to the fall midterms.

METHODOLOGY - This ABC News/Washington Post poll was conducted by telephone Dec. 12-15, 2013, in English and Spanish, among a random national sample of 1,005 adults, including landline and cell-phone-only respondents. Results have a margin of sampling error of 3.5 points, including design effect. Partisan divisions are 30-24-40 percent, Democrats-Republicans-independents.

The survey was produced for ABC News by Langer Research Associates of New York, N.Y., with sampling, data collection and tabulation by Abt-SRBI of New York, N.Y.