Four weeks from today (less, in states with early voting), Americans will stream to the polls and deal a blow to Obama and his agenda. That’s the conclusion of the latest Washington Post/ABC News Poll. ABC sums it up this way:

Increasingly disenchanted with President Obama’s work on the stalled economy, registered voters by an 8-point margin say they’d prefer to see the Republicans take control of Congress — the clearest sign yet of GOP opportunities and Democratic risks in the 2010 midterm elections. A year and a half into his presidency, 51 percent in a new ABC News/Washington Post poll would rather have the Republicans run Congress “to act as a check on Obama’s policies,” vs. 43 percent who want the Democrats in charge to help support those policies. That’s accompanied by a 7-point, one-month drop in approval of Obama’s handling of the economy, to a career low. While Democrats are most at risk, the danger’s not theirs alone. Registered voters by 62-26 percent are inclined to look around for someone new for Congress rather than to re-elect their current representative — the broadest anti-incumbency on record in ABC/Post polls since 1989. …

[Obama’s] job approval rating has slipped to 50 percent, tying his career low in ABC/Post polls, with 47 percent disapproving. Those who “strongly” disapprove outnumber strong approvers by 7 points, the widest such margin to date.

A few highlights: independent likely voters (who outnumber both Republicans and Democrats in the poll) favor GOP candidates by an astounding 53-36 percent margin. The president’s performance on the economy is at the root of the problem (only 43 percent approve of Obama’s handling of the most important issue to voters), but ObamaCare is none too popular either (only 45 percent approve). On every major domestic issue (health care, financial regulation, the economy, and the deficit), voters disapprove of Obama’s performance by between 50 and 56 percent. Seventy-three percent think the economy is staying the same or getting worse. His only bright spot: 55 percent approve of his performance as commander in chief.

Individual races will depend on the strengths and weaknesses of individual candidates, but the landscape is set, and it is extremely unlikely that the electorate’s mood will change. Democrats can spin all they like, but there is no sign of improvement in their fortunes. What is left to be determined is the extent of the damage and how successfully Obama can deflect blame for the implosion of his party.