RELATED: Virginia holds key to the White House

Republican George Allen and Democrat Tim Kaine will likely ride the coattails of their respective party's presidential nominees in a U.S. Senate race in Virginia that will help decide whether Democrats keep control of that chamber.

Every poll shows Allen and Kaine deadlocked months ahead of Election Day. Meanwhile, President Obama is slightly ahead of presumptive Republican presidential nominee Mitt Romney in the Old Dominion, a good sign for Kaine.

The Kaine-Allen race is widely expected to remain tight, assuming Allen emerges unscathed from his primary battle. But Virginia has a tendency to favor home-grown Democrats in statewide races over more liberal Democratic presidential candidates.

The last two Democratic U.S. Senate candidates to run in presidential election years -- former Sen. Chuck Robb and Sen. Mark Warner -- outperformed their party's presidential contender. In 2008, Obama won Virginia by 6 percentage points, while Warner scored a 30-point victory. When Robb lost to Allen in 2000, he still got nearly 48 percent of the popular vote compared to Al Gore's 44 percent.

Successful Virginia Democrats tend to be more moderate than their Washington counterparts, meaning their appeal to independents is greater. Republicans, like Allen, emerge from primaries more conservative. In that respect, Kaine is more likely to appeal to a Romney voter than Allen is to an Obama voter.

"Kaine has a slightly better chance if Romney wins Virginia but only if its by less than a few thousand," Skelley said. "It's easier to imagine a Romney-Kaine voter than it is to imagine an Obama-Allen voter."