The Democratic nomination race so far - Where things stand
Assuming that Ambinder's calculations are correct, in terms of the relative numbers of pledged delegates committed to Obama and Clinton respectively (superdelegates aren't included in this table), the net results of the last six state contests--in Ohio, Texas, Rhode Island, Vermont, Wyoming, and Mississippi--have left matters almost exactly where they stood on February 19, right after the Wisconsin primary. Between Ohio, Rhode Island, and the Texas primary, Clinton picked up a net gain of 18 delegates. Between Mississippi, Wyoming, and the Texas caucuses, Obama picked up a net gain of 19 delegates.
So whereas Obama had 160 more pledged delegates than Clinton on March 3 (the day before the primaries in Ohio, Texas, Rhode Island, and Vermont), he now leads by 161 pledged delegates.
In other respects, of course, various things about the race have changed significantly since March 3. But the bottom line is that Obama remains the front-runner. And my guess is that whatever happens over the next few months, even if the Florida primary and the Michigan caucuses are re-run, (a) Clinton's chances for overcoming Obama's lead in pledged delegates are probably nil, and (b) neither candidate will be able to get nominated without the support of superdelegates. (Still, as we have seen, anything can happen.)