As Romney Gains, Senate Remains Challenging for GOP

When 2012 began, the presidential race looked too close to call, but most analysts thought the Republicans had a good chance to win control of the Senate. The numbers were just too daunting for the Democrats. They had too many seats to defend and too many vulnerable incumbents.

Now, 10 months later, the race for the White House remains very close. But as Mitt Romney's prospects have improved in recent weeks, it is the Democrats who are favored to end up controlling the Senate.

This change happened in a few steps. First, Olympia Snowe announced her retirement. That shifted the apparently safe Senate seat in Maine from the GOP to Angus King. King is now heavily favored to win the Maine Senate race and expected to caucus with the Democrats.

The next step in the Democratic revival was found in Missouri. Incumbent Claire McCaskill was trailing all potential GOP candidates and had the added burden of being closely linked to President Obama. In some states, that might be a good thing, but not in Missouri. Then, Todd Akin won the Republican nomination and immediately put his foot in his mouth. That converted another once likely GOP pickup back to the Democratic column. McCaskill leads by 8 in the latest Rasmussen Reports poll of the race.

That created a situation where Rasmussen Reports now projects that the Democrats are poised to have 48 Senate seats after Election Day and the Republicans will have 47. Five remain tossups, and the GOP needs to win four of them to win control (three if Mitt Romney wins and Paul Ryan gets to cast the tiebreaking vote). It's not impossible, but it's an uphill battle.

One of the five toss-ups -- in Massachusetts -- may be drifting away from the GOP. Incumbent Republican Scott Brown stunned the world in early 2010 when he won a special election to take the seat formerly held by Ted Kennedy. And, it's likely that if Massachusetts voters had a choice simply between Scott Brown and Democrat Elizabeth Warren, Brown would win. However, if the choice is between Republicans or Democrats controlling the Senate, that's a no-brainer in Massachusetts. At the moment, the race remains close, but Warren has a slight edge.

Republicans are also a slight underdog in Ohio, where incumbent Democrat Sherrod Brown has held a slight but persistent lead over Josh Mandel.

In Wisconsin, the GOP nominated four-term Gov. Tommy Thompson, but he trails Rep. Tammy Baldwin. Many say the Democrat has simply run a better campaign.

Races in Montana and Virginia are just too close to call.

None of this is etched in stone. The races are called tossups for a reason, and the dynamics could shift. There are also a few other races that may come into play. In Connecticut, Democrat Chris Murphy is clinging to a narrow lead over Linda McMahon. The Pennsylvania Senate race is getting tighter, as well. A strong finish by the GOP nationally could lead to their party winning control of the Senate.

But, at the moment, that's not the likely outcome.