Even though ten states are voting in the Republican presidential primary tomorrow, most of the media’s attention will likely be directed at Ohio, where the race between Mitt Romney and Rick Santorum remains incredibly close.

NBC News/Marist:
Rick Santorum 34%
Mitt Romney 32%
Newt Gingrich 15%
Ron Paul 13%
other 1%
undecided 6%

Public Policy Polling:
Mitt Romney 37%
Rick Santorum 36%
Newt Gingrich 15%
Ron Paul 11%
Someone else/Not sure 2%

Quinnipiac:
Mitt Romney 34%
Rick Santorum 31%
Newt Gingrich 15%
Ron Paul 12%
DK/NA 7%

The recent polling shows the race basically tied, but there are indications that the recent momentum in Ohio has been moving towards Romney. The Quinnipiac poll from last week had Santorum leading Romney by seven, but now Santorum is trailing Romney by three in their most recent poll.

If Santorum doesn’t win Ohio, tomorrow could be a very bad night for his campaign. Romney is already favored to win between 3-5 of the other ten states tomorrow, and Gingrich holds a big lead in his home state of Georgia. Santorum only has a significant lead in polling in Oklahoma and a dangerously small lead in Tennessee.

If Santorum doesn’t win Ohio, it would likely start a new round of people questioning the viability of Santorum’s candidacy. Ohio is probably a must win for Santorum.