FEBRUARY HAS been a time of trial and tribulation for Hillary Clinton.
It's not simply that Barack Obama has seized the advantage in the Democratic presidential race.
Add to Clinton's woes the inroads her rival has made into her base, plus the way the campaign dynamic has undercut several of her cherished political arguments.
Viewed from the perspective of a few months ago, the progress Obama has made this month is remarkable. On Super Tuesday - the day when Clinton once hoped to wrap up the nomination - he fought her to a basic tie.
Since then, the Illinois senator has dominated, scoring victories over the weekend in Louisiana, Nebraska, Maine, Washington state, and the Virgin Islands.
Then came Tuesday's wins in Virginia, Maryland, and the District of Columbia. Yes, Obama was expected to prevail in all three places. But his showings in Virginia, where he beat Clinton 64 percent to 35 percent, and Maryland, where he bested her 60 percent to 37 percent, were clear indications that his momentum has begun to change the underlying structure of the race.
"I think Tuesday was a turning point for Obama," says pollster Tom Kiley, who has worked in several presidential campaigns. "To have the margins he did, which means he won most major demographic groups pretty much across the board in Virginia and to a lesser extent in Maryland, is really significant."
Indeed, in those two states, exit polls showed Obama beating Clinton among women overall (though not white women), older voters, union households, and less affluent households, groups that have usually been part of her base.
Asked to assess Clinton's situation, a veteran of past national campaigns who supports her in this one put it this way: "Houston, we have a problem! Their whole thing was to wrap it up early, but now it's almost like she has a Rudy Giuliani strategy, pointing down the road to Ohio and Texas."
During a conference call Wednesday with reporters, Clinton's team argued, again, that the March calendar will prove favorable for her. And yet, that contention stops short of being persuasive. Even after March 4 - which features primaries in Ohio, Rhode Island, Texas, and Vermont - the Clinton campaign, despite its lead in superdelegates, doesn't expect to have overtaken Obama, but only to have drawn within 25 delegates of his tally.
And that, of course, assumes that her current leads hold in Texas and Ohio. But should she do poorly next week in Wisconsin, Clinton may find that her support in her must-win states starts to evaporate.
What's more, Obama's February success has worked to blunt several of her candidacy's principal justifications.
Clinton has long maintained that she is not just more experienced than her rival but also better able to withstand Republican general election attacks. But with Obama's winning streak lending him stature and validating him as a figure on at least equal footing with her, the experience argument can't help but lose potency.
Similarly, Clinton's succession of losses, combined with several polls showing her running less well against presumptive Republican nominee John McCain than Obama would, have cast further doubt upon her already debatable claim that she would be the Democrats' best candidate in the fall.
"It is very difficult to argue that you are the most electable candidate if you are losing primaries and not doing as well in the general election matchups as your opponent," observes political consultant Tad Devine, another presidential campaign veteran.
Conceptually, campaigns are a dual between competing arguments, and here's the bottom line as of today: Obama has systematically matched and mastered Clinton's political propositions.
Now, her aura of inevitability shattered, her campaign suffering from shake-ups and internal tensions, and her oft-repeated rationale eroding, Clinton finds herself facing this challenge: To make a compelling case why she would be better than her rival on substantive matters that motivate people to vote.
Candidate and campaign are trying, casting her as a policy expert with solutions for the problems besetting the middle class. They are, for example, stressing that her healthcare plan, with its individual mandate, is more comprehensive than Obama's, which lacks such a requirement. And that she favors bolder action to address the mortgage-foreclosure problem.
As Clinton has shown before, she's resilient. Still, if she can't post a strong showing in Wisconsin on Tuesday, the road to redemption in Ohio and Texas seems likely to grow substantially steeper.
Scot Lehigh's e-mail address is lehigh@globe.com.
