Today’s Potomac primary (Chesapeake primary?) in Virginia, Washington, D.C., and Maryland is expected to deliver another sweep to Obama and add to the woes of the Clinton campaign. Since the draw that was Super Tuesday, she’s been hit by a string of bad news: her $5 million self-loan, her remarkable fund-raising being overshadowed by Obama’s even more remarkable fund-raising, being routed in last weekend’s primaries, her campaign shake-up, and a slew of recent polls that show her to be the weaker candidate against John McCain. Is there a light at the end of the tunnel for Clinton? Or is the tunnel more like that superlong one proposed to run between Long Island and Westchester and destined to deposit her back at home?

• Patrick Healy paints a picture of panic in Hillary-land, with worried donors and supporters clamoring for answers. [NYT]

• Craig Crawford writes that the Clinton supporters are again “spinning doomsday scenarios,” but that their doing so may actually resurrect the campaign, as it has done before. [Trail Mix/CQ Politics]

• Noam Scheiber doesn’t think Clinton can count on winning over superdelegate support if she has fewer pledged delegates than Obama come August. [Stump/New Republic]

• Matthew Yglesias doesn’t buy Clinton’s explanation for losing Louisiana, recalling a time not too long ago when she had more than marginal support among African-Americans. [Atlantic]

• Josh Marshall isn’t sure if Clinton’s Rudy-reminiscent strategy of writing off unfavorable states and focusing on Texas and Ohio will work after a month of losses. [Talking Points Memo]

• And about Texas: Andrew Sullivan looks at the crazy delegate math there and says that, even if Clinton wins by five points, she’ll lose by three delegates. [Atlantic]

• But E.J. Dionne Jr. writes that there’s still a large swath of middle-aged working-class Hillary supporters who are immune to Obama’s charms. [Washington Post]

• John Dickerson thinks it’s too early to count Hillary out just yet: Obama, as front-runner, will face increasing scrutiny, and she actually has a more hard-core group of supporters and can win over the superdelegates. [Slate] —Dan Amira

For a complete guide to presidential candidates Hillary Clinton and Barack Obama — from First Love to Most Embarrassing Gaffe — read the 2008 Electopedia.