Two tides swept over American politics last winter. The first was the Obama tide. Barack Obama came into office with an impressive 70 percent approval rating. The second was the independent tide. Over the first months of this year, the number of people who called themselves either Democrats or Republicans declined, while the number who called themselves independents surged ahead.

Obama’s challenge was to push his agenda through a Democratic-controlled government while retaining the affection of the 39 percent of Americans in the middle.

The administration hasn’t been able to pull it off. From the stimulus to health care, it has joined itself at the hip to the liberal leadership in Congress. The White House has failed to veto measures, like the pork-laden omnibus spending bill, that would have demonstrated independence and fiscal restraint. By force of circumstances and by design, the president has promoted one policy after another that increases spending and centralizes power in Washington.

The result is the Obama slide, the most important feature of the current moment. The number of Americans who trust President Obama to make the right decisions has fallen by roughly 17 percentage points. Obama’s job approval is down to about 50 percent. All presidents fall from their honeymoon highs, but in the history of polling, no newly elected American president has fallen this far this fast.