Romney, Santorum tied in Ohio

(CNN) – Voters in Ohio, who face a key Republican primary on Tuesday, are nearly split between Mitt Romney and Rick Santorum, according to a poll released Sunday.

The survey from NBC/Marist showed Santorum with the support of 34% of likely Republican primary voters in the Buckeye State, two points ahead of Romney, who was at 32%. The margin is was well within the poll's sampling error of plus or minus 3.4 percentage points.

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The two other candidates in the race - former House Speaker Newt Gingrich and Texas Rep. Ron Paul - both stood well behind the frontrunners. Gingrich had the support of 15% of Ohio Republican voters, while Paul was at 13%.

The NBC/Marist poll was conducted February 29-March 2, after primaries in Michigan and Arizona, which took place February 28. Romney swept those contests, though his three-point margin of victory in Michigan was seen by many as a weak showing in the state where he grew up while his father was governor.

Ohio is one of the largest states to vote Tuesday, with 66 delegates. The state holds an open primary, meaning independents and Democrats are allowed to vote in the GOP contest.

Ohio will also be a key battleground in November's general election. The NBC poll showed President Barack Obama beating each of the four GOP candidates by double digits in head-to-head matchups. Ron Paul fared the best, trailing Obama by 10 points, 48% to 38%. Romney trailed the incumbent by 12 points, 50% to 38%.

The Ohio survey was taken by phone from 820 likely GOP voters. The general election matchups polled 3,079 registered Ohio voters.

In another Super Tuesday state, Virginia, the NBC/Marist poll showed Romney with a sizeable lead over Paul, his only competitor in the state. Both Gingrich and Santorum failed to qualify for Virginia's GOP primary ballot after not submitting the proper number of petitions to the state’s Republican Party.

Romney led Paul 69% to 26% in Virginia, according to the poll. When Romney was matched up with the candidates not on the ballot, the former Massachusetts governor still held his lead, though by a smaller margin, getting 36% to 28% for Santorum.

Like Ohio, Obama handily won matchups with the GOP contenders in Virginia. Obama led Romney by 17 points in the commonwealth, and beat Paul by 21 points.

The Virginia poll, also taken February 29-March 2, was taken by phone from 2,518 registered voters, and 529 likely GOP voters. The sampling error was plus or minus 4.3 percentage points.