Democrats and Republicans rarely agree on anything, but assailing Gov. Charlie Crist in his bid for the U.S. Senate has become a bipartisan affair.

GOP candidate Marco Rubio and Democrat Kendrick Meek have all but ignored each other lately, concentrating instead on capturing the middle ground that independent Crist has claimed for himself. In practice, this means throwing Crist like hot potato toward the other side.

“Home is where the heart is. And for Charlie Crist, home is with the GOP,” the announcer says in Meek’s latest radio ad.

Republicans certainly aren’t claiming him, though.

“I always knew I’d have to run against two people who support the Barack Obama agenda — I just didn’t know I’d have to run against them at the same time,” Rubio is quoted as saying in one of his campaign’s press releases.

It’s odd to see the two major parties slamming something other than each other — let alone slamming something together in unison.

Crist’s evasiveness — his unwillingness to say which party he would caucus with if elected and his shifting position on the health care reform bill — makes him an easy target and doubtless plays a role in the opposing campaigns’ focus. But end-game strategies also dictate Crist as the competitor to hit.

Meek, for example, needs to pick up more Democrats and left-leaning independents to win the race.

“With an expected turnout of 43 percent Democrats and 40 percent Republicans, Kendrick needs to win 75 percent of registered Democrats and just 17 percent of the registered Independent vote to secure 35 percent of the vote total,” reads a Meek campaign strategy memo released after the Aug. 24 primary.

The latest poll for which crosstabs are publicly available, Public Policy Polling’s pre-primary survey from Aug. 23, shows Meek falling well short of that goal, with support among Democrats and independents at 39 percent and 4 percent, respectively.

Crist, meanwhile, draws support from 38 percent of Democrats and 50 percent of independents. Clearly, Meek needs to convince them that Crist is an unacceptable choice. To that end, Meek is casting the governor as a lifelong member of the GOP. The campaign released a new radio ad this week that excerpts recordings of past statements by Crist in order “to show he is a lifelong conservative Republican with the record to prove it.”

The campaign also enlisted a well-known liberal firebrand, Rep. Alan Grayson of FL-8, to send an email on behalf of Meek.

“‘She’d do a great job.’ That’s what Charlie Crist said about Sarah Palin as President of the United States. If that doesn’t tell you where he stands, then I don’t know what does,” Grayson writes. “Crist may want us to forget he’s a conservative Republican, but the past keeps coming back to haunt him. That’s just one reason I’m supporting Kendrick Meek.”

For his part, Rubio has little incentive to attack Meek, who trails him by 19 and 23 points in the last two polls. Crist has fought back and forth with Rubio for leadership of the race and is the much more immediate threat.

The fact is clear in talking to Rubio spokesman Alex Burgos, who, in attacking Crist, almost defends the opposition party’s candidate.

“Kendrick Meek is not trying to fool anybody about who he is — I mean, he is a devout liberal who is supporting this agenda coming out of Washington and has really been a rubber stamp for it,” Burgos told Battle ‘10. “Charlie Crist is trying to fool voters.”

Crist spokesman Danny Kanner said his campaign’s strategy is to continue to put out a positive message, and suggested that the dueling attacks show Crist is doing something right.

“It’s not surprising that they revert to the same old political gamesmanship that’s gotten our country into this mess,” Kanner told Battle ‘10. “I think it shows that even the partisan politicians know that voters want an independent senator who’s going to go to the Senate and fight for them, not for political party bosses.”

As poll numbers shift, Meek and Rubio may again find themselves in more directly confrontational positions. Their appearance on “Meet the Press” this Sunday, sans Crist, will certainly give the two plenty of opportunity to get back to the more familiar jabs of left versus right.

But until then, enjoy the bipartisan unity, courtesy of Charlie Crist.