By HARSH SETHI

Barack Obama and John McCain will be carefully watching Virginia early tonight. Television viewers should, too. The state is in the first wave to close polling places, at 7 pm Washington DC time. The results will be telling. Obama has pushed hard to flip the state, which hasn’t backed a Democratic presidential candidate since 1964, and he led in pre-election polls.

“An Obama win in Virginia would be a sign the race is over,” said John Fortier, a research fellow at Washington’s American Enterprise Institute who wrote a book about the U.S. Electoral College. “If he wins Virginia, he is likely to be doing well elsewhere.”

Virginia’s results may signal a tidal wave of states turning Democratic after backing Republican President George W. Bush in 2004.

Another on the watch list at 7 pm is Indiana, which also hasn’t backed a Democrat since Lyndon Johnson won in a nationwide landslide 44 years ago.

Ohio follows Virginia and Indiana with a scheduled poll closing time of 7:30 pm Washington DC time. In 2004, the state and its 20 electoral votes remained too close to call until the next day, when Democrat John Kerry conceded. For McCain, the state is critical: No Republican has ever won the White House without claiming Ohio.

North Carolina and West Virginia, two other states Obama is contesting that went Republican in the last two elections, close at the same time as Ohio.

Half an hour later, at 8 pm, the biggest of the battleground states, Florida, is slated to close all its polls, along with those in Michigan, Missouri, New Hampshire and Pennsylvania.

“It is nearly impossible for McCain to win without winning Ohio, Virginia, and Florida,” Fortier said. Bush won all three in 2004, ending up with 286 Electoral College votes. A candidate needs 270 to get to the White House.

The first poll closings may also offer early clues on Senate and House races. Kentucky’s balloting is due to finish by 7 pm and attention will be on Senate Minority Leader Mitch McConnell’s efforts to hold his seat. A loss for the Republican would bolster Senate Democrats’ chances of getting to the 60 seats they need to block a filibuster.