WASHINGTON — The political conventions behind them and three debates ahead, Barack Obama and Mitt Romney now race against the calendar toward Nov. 6.

They have two months to deploy millions of dollars in ads, catch those voters who cast ballots weeks before Election Day, and log umpteen miles in a handful of crucial states — all while worrying what surprising news or candidate slip-up might set the whole enterprise on its ear.

Obama and Romney have huge staffs to help keep it all straight, of course. But you don’t.

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So far, polls show a tight race. But forget everything you’ve heard so far. In polling, only the newest numbers count — and the numbers capture a clearer picture beginning in September. It’s time to pay attention.

One obvious reason: Summer fun is over, and voters are finally following the campaigns. Polling from the Pew Research Center in 2008 showed the share following the campaign “very closely” just about doubled from 28 percent in late August to 57 percent just before Election Day. With the public more attuned to day-to-day developments, the potential for big shifts in the polls is amplified.

Another reason is less apparent: Many polls get more accurate in the final two months, as pollsters make refinements in their hunt for likely voters, the elusive target for election surveys.

Money is a huge factor in this election, and one of the hardest to track.

The presidential race is expected to cost $2 billion or more, between official campaign expenses and super PAC ad spending. It’s the first election since federal courts unraveled rules that had restricted how money could be spent in political races.

Outside groups can now raise and spend unlimited sums of cash with the help of millionaires and billionaires, who sometimes hide their identities as donors.

The result is a gusher of ads flowing through Monday Night Football and prime-time sitcoms until Election Day.

Something to watch for: In some states, the TV ads may suddenly vanish. That’s a sign that one of the campaigns has given up hope there and moved resources to a state that’s still in play.

And watch how this plays out: Romney’s side is far outspending Obama’s. Can the president narrow the gap?

Romney and his super PAC allies have spent more than $245 million on ads since the general election began in early April, according to advertising tracking data obtained by The Associated Press. That spending began outpacing the Democrats in mid-July, and the trend is expected to continue. By comparison, Obama and super PACs working in his favor have spent roughly $188 million since April.

This race is all about jobs and the economy, so government reports and stock market swings take on outsized importance.

The Labor Department reported sluggish job growth Friday, as employers added 96,000 jobs in August. The unemployment rate fell to 8.1 percent from 8.3 percent in July but that was only because more people gave up looking for work.

Romney immediately seized on the latest numbers as further evidence that Obama’s efforts to fix the economy have failed. The president said the numbers weren’t good enough but sought more time for the recovery.

The Labor Department will release two more monthly jobless reports, including one just four days before Election Day.

Also watch the Federal Reserve’s actions when it meets next week. It could dramatically boost the sluggish economy by announcing a third round of bond purchases designed to push long-term interest rates lower.

The race is so tight that one misstep in the three presidential debates could greatly influence who wins.

The first debate, Oct. 3 in Denver, focuses on domestic policy.

Two weeks later, on Oct. 16, the Obama and Romney meet for a town hall-style session in Hempstead, N.Y.

On Oct. 22, two weeks before the election, foreign policy is the topic for the last presidential debate in Boca Raton, Fla., a swing state critical for the candidates.

And on the undercard, Vice President Joe Biden debates Rep. Paul Ryan on Oct. 11 in Danville, Ky.

Watch for unexpected news in the final weeks of the race that could shift things in one candidate’s favor. Past surprises have touched on major events — developments in the Vietnam War, the Iran hostage crisis, the Iran-Contra probe — and less weighty ones, such as George W. Bush’s two-decade-old drunken driving arrest.

This year, there’s speculation that Iran could pop up again, possibly in the form of an Israeli military strike against Iran’s suspected nuclear program.

A unilateral Israeli attack on Iran could set off a chain reaction. Tehran’s counterattack could include strikes on U.S. personnel and bases in the region; the U.S. military might come to Israel’s aid; oil prices would skyrocket; spreading conflict could light the short fuse that is the Middle East.