Spoiler alert? (Photo by Gage Skidmore

Former Massachusetts Gov. Mitt Romney should skate to an easy victory in Virginia’s Republican presidential primary tomorrow. After all, his current rival, former Pennsylvania Sen. Rick Santorum isn’t even on the ballot, nor is moon aficionado and former House Speaker (and actual Virginia resident!) Newt Gingrich.

The only other candidate joining the often flagging frontrunner on tomorrow’s ballot is Rep. Ron Paul, whose campaign was the only other one organized enough to meet Virginia’s stringent ballot-access rules that require candidates to collect the signatures of at least 10,000 residents. Gingrich came up short ahead of the filing deadline last December and Santorum didn’t even bother applying, leaving just the robotic but still-probably-inevitable Romney and the entertaining but no-chance-in-hell Paul to duke it out for the Old Dominion’s 46 delegates at stake.

Romney picked up a key Virginia endorsement yesterday when House Majority Leader Eric Cantor announced his support on Meet the Press. But even with Cantor’s backing, the Romney camp might find tomorrow’s election more vexing than it expected if Paul can nip away at its heels in enough places, especially if frustrated Santorum backers want to cast an “anyone-but-Romney” vote, WAMU reported this morning.

“I think Mitt Romney probably wins, but I do think you’ll see strong Ron Paul,” says [Rep. Morgan] Griffith. “One, he’s strong in the state, and two, I think he may get some folks that decide they’re going to vote for him instead of voting for Romney in order to send a message about Santorum and Gingrich not being on the ballot.

One group we think might be frustrated by the lack of Santorum—fans of Virginia’s newly passed bill requiring women considering terminating pregnancies to first undergo ultrasound procedures.

Another group that might be able to mess around with Romney’s all-but-guaranteed win: Democrats. Virginia runs an open primary, meaning any registered voter can show up and request a ballot. One Alexandria resident WAMU spoke with said he’s voting for Paul tomorrow not because he’s some hardcore libertarian, but because “it would help to derail the Romney nomination,” thus making Romney an easier matchup for President Obama in the general election.

Of course, Paul will earn plenty of votes on his own, The New York Times’ Nate Silver projects, especially in deep rural pockets and around the University of Virginia in Charlottesville. He probably won’t garner enough to carry the entire state, but Paul could pick off one or two congressional districts. Virginia, which has 46 pledged delegates to distribute tomorrow, awards 13 to whichever candidate gets a statewide majority and divides the other 33 across its congressional districts.

And Paul’s been campaigning somewhat hard in Virginia. Last Tuesday, while Romney and Santorum awaited results in the MIchigan and Arizona primaries, Paul was on the ground in Springfield.

But even if flummoxed Santorum fans and mischievous Democrats manage to turn what should be an easy-lift victory for Romney into a minor headache, a two-candidate primary is still pretty boring. Forget Santorum and Gingrich—it’d be fun if any of these people were on the ballot, too.