WASHINGTON — As Hillary Clinton struggles to put her campaign back on the rails after eight successive losses to Barack Obama in states across the country, the sense of inevitable nomination that earlier surrounded her has suddenly switched candidates.

With Wisconsin and Hawaii Demo-crats voting today, and primaries in Texas, Ohio, Rhode Island and Vermont two weeks later, the aura of inevitability is now leaning to Obama, seen not so much from polling figures as in Clinton's behavior on the ground.

The former first lady's resort to negative comments in rallies and television commercials in Wisconsin signals her awareness that the growing perception of an Obama runaway train must somehow be stopped. For a candidate with high negative poll ratings herself as a polarizing figure, Clinton's new strategy is a highly risky one.

It's particularly so in light of Obama's major campaign pitch that the country is tired of divisive political bickering and can be cured only by his own brand of "post-partisanship." Clinton's accusations that Obama is all inspiration and no solutions is not far from her derisive comment in Texas about President Bush — that he is "all hat and no cattle."

Clinton's television ad tries to put Obama on the defensive by trumpeting his rejection of her call for another one-on-one debate in Wisconsin. Her spokesman, Howard Wolfson, said on PBS it's "the old politics" to refuse to debate in a state where you're ahead in the polls. But saying so only advertises Obama's apparent strength there on the eve of the primary.

The Obama campaign responded with an ad noting there already have been 18 debates involving the two surviving Democratic candidates, and that two more are slated soon in Texas and Ohio — though after the Wisconsin vote. David Axelrod, Obama's chief strategist, said on PBS that his candidate would rather spend the time meeting voters, which has been his strong suit so far.

Clinton on the stump also has continued to argue she is the candidate of substance as well as experience. But in a recent exchange of policy proposals on the economy, the issue said to be first in voters' concerns now, it was hard to find substantial significant differences in what each is offering. Both are courting middle-income and blue-collar workers who are the core of the Democratic constituency.

On the issue about which there is the clearest difference between the two — launching the war in Iraq — Clinton is conspicuously on the defensive over her October 2002 vote for the resolution authorizing use of force. Obama at the time opposed it as "a dumb war" in a Chicago speech in seeking the Senate seat he now holds.

The closeness of the delegate count between them has raised much speculation about how convention superdelegates — 796 party leaders and members of Congress unelected in the primaries and caucuses — might well decide the outcome. Clinton has led among them, but already erosion has begun.

She suffered a major defection the other day from Rep. John Lewis of Georgia, a hero of the historic 1965 civil rights march in Selma. He told the New York Times that as a superdelegate he will vote for Obama to avert a convention fight if no candidate achieves a majority in advance.

Lewis joined another Georgia black Democrat, Rep. David Scott, in saying he will switch from Clinton to Obama at the party's national convention in Denver. Lewis' prior endorsement of Clinton was considered a coup of great proportions, and his move, and Scott's, could set off a string of similar actions by other superdelegates, especially among African-American leaders.

Lewis and Scott picked up on a widely noted argument by another black Democratic leader, Donna Brazile, a member of the Democratic National Committee, and campaign manager for then-Vice President Al Gore in 2000, that unelected superdelegates should not override the will of voters who turned out for either Clinton or Obama.

That argument could nullify any Clinton lead among the superdelegates if the choice came to them. But the way the voting has been going for Obama, the decision may not come to that after all.

Jules Witcover's latest book, on the Nixon-Agnew relationship, "Very Strange Bedfellows," has just been published by Public Affairs Press.