The death of Edward Kennedy has given the Democrats a real -- if short-term -- look at life in the Senate without 60 votes. Given the worsening political environment for the party and President Obama, it looks more possible than ever that Republicans can keep Democrats under 60 in 2011-12 as well.

On paper, the GOP has more vulnerable seats on the table than do Democrats. They have to defend open seats in two states carried by Obama (Ohio and New Hampshire) and one in a state Obama barely lost (Missouri). Republicans breathed a sigh of relief when Sen. Jim Bunning, their most vulnerable incumbent, chose to retire. Even so, holding the seat isn't a slam dunk. Meanwhile, Democrats have just one open seat in real danger today (Illinois) and just one incumbent, Connecticut's Christopher Dodd, who has been running consistently behind his potential GOP opponents in polling. Both of those states, of course, are deep blue.

When the political environment is bad enough, even mediocre candidates can win.

Yet it's also clear that as Obama's job approval ratings fall, it's taking a toll on Democratic incumbents who, earlier this year, were seen as relatively safe. New polls show Democratic Sens. Blanche Lincoln (Ark.), Michael Bennet (Colo.), Harry Reid (Nev.) and Kirsten Gillibrand (N.Y.) as vulnerable. A GOP poll released in late July showed popular North Dakota Gov. John Hoeven (R) handily beating Sen. Byron Dorgan (D).

The open seat in Delaware is still a tantalizing possibility for Republicans should moderate GOP Rep. Michael Castle run. And while California Republicans haven't elected a senator since 1988 (and haven't beaten an incumbent Democratic senator since 1976), former Hewlett-Packard CEO Carly Fiorina (R) is, on paper at least, the strongest candidate to face Sen. Barbara Boxer (D) in years.

Even so, Republicans have been hobbled in many of these states by a weak bench (Arkansas and Colorado) or a lack of interest by their strongest potential candidates (Nevada, New York and North Dakota). In Nevada, Rep. Dean Heller and U.S. District Judge Brian Sandoval have said no to challenging Reid. In New York, Rep. Peter King announced on Monday he wouldn't challenge Gillibrand, and no one expects former Gov. George Pataki to run either. And GOP insiders are highly skeptical that Hoeven will challenge Dorgan in North Dakota.

Still, if we learned one lesson from 2008, it was that when the political environment is bad enough (or good enough, depending on your perspective), even mediocre candidates can win. Jeff Merkley (D) was no one's first pick to run against then-Sen. Gordon Smith (R) -- nor was Kay Hagan (D) considered a recruiting coup in North Carolina. At this point in 2007, Smith had $3.5 million in the bank while Sen. Elizabeth Dole had $1.7 million.

One bit of good news for Democrats is that the poor political environment hasn't deterred one of their strong recruits from running. Rep. Charlie Melancon's announcement last week that he'd challenge Sen. David Vitter wasn't a surprise; redistricting in 2012 is a huge threat to Melancon, whose seat may be sacrificed. But it would also have been easy for him to have looked at the current climate and said "I'd rather take my chances in '12" than fight against an almost certain headwind in '10.

What can worried Democrats do? For one, they can push to vote sooner rather than later on some sort of health care legislation. It may not give Democrats the boost -- either politically or policy-wise -- they were hoping for. But the longer it sits out there, the more energized the GOP gets. And that energy ultimately becomes self-sustaining.

I asked two smart strategists -- one Republican and one Democrat -- if they thought it'd be wise for Democratic incumbents with big war chests to start spending money proactively in hopes of insulating themselves from the bad climate. It could work, said one, but only if the incumbent has something relevant to say; just going on TV kissing babies is a waste of money. Of course, the two issues that top voters' list of concerns -- the economy and health care -- don't call for bragging from Democrats.

For those incumbents who are either brand new (say Bennet) or already defined as polarizing (Reid), it's almost impossible to build/rebuild a brand without spending the kind of money that only big corporations, not campaigns, have on hand.

In other words, Democrats may just have to ride this storm out and hope that things get better in '10. Their big war chests, meanwhile, can be put to better use in defining (read: attacking) their ultimate opponent.

At this point, Democrats have about as many vulnerable and potentially vulnerable seats as Republicans. This suggests that the 2010 elections could be a wash -- Democrats pick up a couple of open seats while Republicans knock off an incumbent or two, and we're right back at 60. But it's very rare that races break so cleanly in the end. Usually the political environment pushes the closest races one way or the other, giving one side 60 to 70 percent of the wins.

Of course, given the trouble Reid has had corralling his members on energy and health care legislation, 60 seats no longer seems quite as intimidating -- or appealing -- as it did back in 2007.