LANSING, Mich. - Mitt Romney is neck-and-neck with-Rick Santorum in Michigan but has pulled far ahead in Arizona on the eve of key primary contests in both states, according to new polls.
The Public Policy Polling (PPP) final survey of likely Michigan primary voters, conducted Sunday and Monday, found Santorum edging Romney by a margin of 38 percent to 37 percent -- a difference within the poll's margin of error.
The poll, however, did find momentum swinging toward Santorum in the final hours before the Michigan contest, with the former Pennsylvania senator holding a 39 percent to 34 percent advantage among those polled on Monday, the second day of polling.
And among those polled Monday who had not yet voted in the primary, Santorum's lead over Romney was even bigger -- 41 percent to 31 percent.
But the pollsters said late Monday night that while momentum was swinging to Santorum, Romney held a massive 56 percent to 29 percent lead among the Michigan voters who have already cast their votes -- nearly one in five voters.
Texas Rep. Ron Paul was in third place overall in the two-day poll with 14 percent, while former House Speaker Newt Gingrich drew nine percent.
In Arizona, Romney has pulled well ahead of Santorum and the rest of the presidential field, according to a separate PPP poll conducted Sunday.
The former Massachusetts governor secured 43 percent in that poll, compared to Santorum's 26 percent, Gingrich's 18 percent and Paul's 11 percent.
Also, nearly half of those planning to vote had already cast their ballots, and Romney had a 48 percent to 25 percent advantage over Santorum among that group.
The pollsters said that lead makes it "nearly impossible" for Santorum to catch up.
In Michigan, PPP surveyed 922 likely Republican primary voters. The poll's margin of error is 3.2 percent. PPP polled 515 likely Republican primary voters for its Arizona survey. The margin of error for that poll is 4.3 percent.
No matter the top finisher in Michigan, Romney and Santorum stand to split the 30 delegates at stake because Michigan distributes delegates proportionally. By contrast, Romney is favored to capture all 29 delegates in Arizona, which features a winner-take-all system.
Romney has 123 delegates to 72 for Santorum, 32 for Gingrich and 19 for Paul in the Associated Press count, with 1,144 required to win the party nomination at the Republican National Convention in Tampa, Fla.