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Challenges across the policy spectrum are keeping Barack Obama in political peril, with the public divided on initiatives ranging from Senate-supported immigration reform to Obama's signature health care law.

As he readies a new pitch on economic growth, the president's job approval rating has slipped below 50 percent for the first time since September in ABC News/Washington Post polls. Even with a recovery in consumer sentiment, just 45 percent approve specifically of his handling of the economy, and 60 percent say the country's headed seriously off on the wrong track.

See PDF with full results and charts here.

Congress, for its part, manages just a 21 percent approval rating - up by 5 points since March to more than a two-year high, but still dismal by any measure. And whatever Obama's challenges, this poll, produced for ABC by Langer Research Associates, finds that Republicans are hardly rejoicing: They're far more critical of their own party's leadership than are Democrats of theirs, with 52 percent of Republicans and Republican-leaning independents - a new high by a substantial margin - saying the GOP's going astray.

IMMIGRATION - Among prominent initiatives, Americans divide essentially evenly, 46-44 percent, on the Obama-supported, Senate-passed immigration reform law, with strong critics well outnumbering strong supporters. Reflecting the view of House Republican leaders, more support breaking the bill into pieces for further consideration rather than a single up-or-down vote, 53-32 percent.

Views on the Senate bill seem to reflect the fact that it's got something for partisans on both sides to dislike - particularly Republicans, just 29 percent of whom support the measure, vs. half of independents and 55 percent of Democrats. ABC/Post polling has found much more support for a path to citizenship among Democrats than Republicans, and much more support for $46 billion in stricter border control among Republicans than Democrats. The bill contains both.

Ambivalence produced by the disparate elements of the Senate bill shows through in this result: On one hand, 66 percent of Hispanics support the measure. On the other, even Hispanics divide on whether the bill should be handled piecemeal or as a whole.

If a path to citizenship for undocumented immigrants fails to go forward, Americans are more apt to say they'd be disappointed, 50 percent, than relieved, 40 percent, reflecting continued greater support for that element of reform. Those who'd be disappointed say by a broad margin that they'd blame the Republicans in the House over Obama if the effort fails.

Just 13 percent say they'd be "angry" if a path to citizenship fails, but that includes a disproportionate share of Hispanics, a growing group with political clout the Republicans, in particular, sorely need.

HEALTH CARE - Another top issue, health care reform, offers no break from controversy. Just 42 percent of Americans support so-called Obamacare, 3 points from the fewest in ABC/Post polls since mid-2009, while 49 percent oppose it. Strong opposition exceeds strong support by 14 points, near the average. Partisanship continues to run high on the law, and tellingly, its support among Democrats, 58 percent, fails to approach the 72 percent opposition among Republicans.

Americans divide by 51-45 percent on the administration's decision to delay the part of the law requiring employers to provide insurance coverage or pay a fine. And they split almost precisely, 48-46 percent, on whether that delay means the law is so flawed it should be dropped entirely, or is just the kind of thing that happens when changes are made to a complex system.

OBAMA - These views, as noted, make for tough sledding for Obama, who's been stuck at or very near 50 percent approval for much of the past year, with a slight re-election-related bump that's since faded. His overall approval rating in this poll, 49 percent, last was seen Sept. 9.

Among other challenges, the pace of economic recovery looks too slow to produce much in the way of political payoff. That's perhaps no surprise, with unemployment at a stubborn 7.6 percent, or 14.3 percent using a more inclusive definition. But economic approval is moving the wrong way for Obama, who's gone from 50 percent on the issue with a post-re-election boost in December and January to 45 percent now.

That isn't to say Obama's getting no respite; his approval rating on the economy fell as low as 35 percent back in fall 2011, and his predecessor, George W. Bush, saw 22 percent approval on the economy in September 2008.

Similarly, while 60 percent say the country's headed on the wrong track - a sentiment with a strong economic component - that's down from a recent high of 77 percent in fall 2011 and a record 90 percent in fall 2008. As not-great as things are, they've been worse, a point Obama may seek to make on his campaign-style tour focused on economic issues this week.

PARTY TIME - Part of the public's grouchy political sentiment may reflect an expressed desire for greater comity than Washington customarily exhibits; 68 percent say it's more important for political leaders to cooperate on important issues than for them to stick with their positions (26 percent).

But there are limits; notably, support for cooperation drops to 48 percent among "very" conservative Americans, a strong voice within the GOP, a result that marks the limitations on their leaders' range of movement.

Indeed, as noted, Democrats and independents who lean toward the Democratic Party are generally pleased with their leaders' efforts; 72 percent say Democratic leaders are taking the party the right direction. (Easier to say, perhaps, when your party holds the White House.)

It's a far different story on the Republican side, where half as many partisans and Republican-leaning independents, 37 percent, say their leaders are taking the GOP in the right direction. Fifty-two percent instead say their own leaders are headed the wrong way, up 20 points from last August (when the White House seemed winnable) and a majority for the first time in six poll results dating to 1994.

That disaffection is apparent in another measure: Just 21 percent of Americans in this survey identify themselves as Republicans, matching the fewest since November 2009. GOP allegiance has dropped from an annual average of 31 percent in 2003 to annual averages of 23 or 24 percent the past five years straight.

Then again, just 31 percent say they're Democrats; more, 37 percent, identify themselves as independents. Politically unaffiliated Americans have outnumbered Democrats and Republicans alike almost continuously for four years, a record, by far, in ABC/Post polls dating to 1981.

METHODOLOGY - This ABC News/Washington Post poll was conducted by telephone July 18-21, 2013, in English and Spanish, among a random national sample of 1,002 adults, including landline and cell-phone-only respondents. Results have a margin of sampling error of 3.5 points, including design effect.

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.