If Senate Democrats think 2010 is a tough cycle, just wait two more years.

They’ll probably hold the Senate majority Tuesday — with a couple of seats to spare, most analysts believe. But 2012 2012 is a different story.

showOdiogoReadNowButton (_politico_odiogo_feed_ids, ‘Tougher road ahead for Senate Dems’, ‘0’, 290, 55); Listen

VIDEO: Driving the day

runMobileCompatibilityScript(‘flashObj651471147001’);brightcove.createExperiences();

POLITICO 44

//

By then, Republicans will be poised to take control of the Senate — with pickup possibilities scattered across the map and a much narrower base of their own to defend.

It’s not simply the lopsided mathematics — with at least 21 Democratic seats on the table in 2012, including two independents who sit with the Democrats, compared with 10 Republicans. It’s where the seats are located.

Start with Democratic seats in three states where President Barack Obama lost in 2008: Nebraska, North Dakota and Montana.

Then go down a list of where Democrats are poised to lose Senate battles this year — Ohio, Florida and Missouri, for example — and Democrats will be right back at it in 2012, defending seats there again.

Throw in some bona fide tossup states — Virginia and New Mexico — and it’s pretty hard not to picture Republicans picking off the handful of seats needed to take control, if Tuesday goes as well for the GOP as experts expect.

But that’s still two years out. Even National Republican Senatorial Committee Chairman John Cornyn has said he expects the Republican takeover effort to be a “two-cycle process,” continuing into 2012.

There is one X factor: Obama himself. Unlike this year, Democrats expect him to be at the top of the ticket, and they hope some of his appeal to the Democratic base will spread to candidates down the ballot, as it did in 2008. And if Obama can improve his standing with voters, maybe even recapture some of those that independents lost to the GOP this year, then Senate Democrats will be in better shape in 2012.

Democrats note that for all the Senate seats in potentially hostile territory, several are in states that Obama carried in 2008 and would be high on his list to win again in 2012: Pennsylvania, Washington, Connecticut and Michigan.

Florida and Ohio are must-wins for Obama as well, if he hopes to stay in the White House, and all that effort could bring Democratic senators along for the ride.

“We have more incumbents up than they do, but the fact that it’s a presidential year and so many incumbents are in Obama ’08 states will be an important advantage,” said Fred Yang, a pollster who works with several Democratic senators.