Beau Biden isn’t running for Senate. Phew.

Beau and Joe Biden. Click image to expand.
Vice President Joe Biden with his son Beau

Democrats may be disappointed by Beau Biden’s decision not to run for Senate in Delaware. But there may be a silver lining: Beau Biden is not running for Senate in Delaware.

Biden was a Democratic favorite but by no means a shoo-in. Polls showed him trailing Republican Rep. Mike Castle consistently since April. And Castle is a good campaigner. Over four decades in state politics, he’s never lost a race. Biden, meanwhile, won his only election in 2006 by a mere five points. Still, Democrats rallied behind Biden because he was the best they had.

Or maybe not. In a year when Democrats are preparing to get clobbered, Biden would have played into many of the narratives that swept Scott Brown into office in Massachusetts last week. In that context, Biden has several glaring weaknesses:

He’s the Man. Scott Brown ran against the Democratic establishment and won. You don’t get more Democratic or more establishment than Biden. It would be a little rich for a septuagenarian Republican to run on a platform on change. But anti-establishment sentiment would likely overcome any cognitive dissonance. Now, whomever the Democrats choose instead will likely be an unknown who can run more credibly as an outsider.

He’s the son of the Man. The appearance of nepotism would have hurt. Biden’s election as attorney general in 2006 was his first foray into political office. Since then, he’s had a heavy work load, plus a high-profile new case against a pedophile pediatrician. But against a Republican with 40 years of experience, Biden’s four years would look rather paltry. Castle would also question whether Biden’s fast rise was due to talent or his last name. Massachusetts Democrats may have loved Ted Kennedy, but they chafed at the notion that the seat belonged to Kennedy, or any Kennedy, or any Democrat. Delaware Democrats might think along the same lines.

The race would reflect on Joe. However much the White House tries to distance itself from the campaign, Beau’s ups and downs would likely become the administration’s—and vice versa. The White House would have to answer questions about the young Biden’s inevitable flubs, while Biden would be forced to answer for administration policies, even if he has nothing to do with them. In a year when Democrats will try to distance themselves from the White House’s unpopular policies—health care reform, the bailout, the stimulus—Beau would be especially tarred.

Joe would reflect on the race. Not only would the White House be asked to answer for Beau’s mistakes—it would probably respond. Joe Biden’s apparent inability to keep his thoughts to himself was a catalyst for Beau’s announcement that he wouldn’t run. (He reportedly asked a journalist to talk his son into it, because Beau didn’t want to run. Biden’s office has a different account.) It’s hardly speculation to assume that Joe would have continued to weigh in, for the worse.

Castle might get Scozzafava’d. Any moderate Republican who’s been around as long as Castle has cast votes that aren’t going to sit well in the current climate. Among them is his vote for cap and trade. During last year’s infamous town halls, Castle drew heat from conservatives for being “one of the eight Republican traitors.” (He was also booed for asserting that Barack Obama is a U.S. citizen.) Now a tea party activist is considering challenging Castle from the right. If that happens, Democrats could be better off than expected—no matter who they run.

That’s not to say Democrats are in much better shape without Biden than with him. But his decision not to run seems like an unmitigated blow only if you ignore the alternative.