Good Tuesday morning. Hope you're not too tired: We're just one-quarter of the way through the busiest week in politics in recent memory. Here's what Washington is watching today:

-- The Senate continues debating amendments to the FISA bill today, a day after Republicans failed to end debate and Democrats failed to extend the program by 30 days. President Bush highlighted the program in last night's State of the Union, urging Congress to take action. House members take up the economic stimulus package today, which is expected to sail to passage with only token opposition from the far right and the far left.

-- The political world, though, is focused on Florida, which the Miami Herald modestly casts itself as "a barometer for the country." Over a million people have already voted in the state's closed primary, and the state's booming Hispanic, retired and conservative electorates will ultimately decide the direction of the race. Win two out of three of those constituencies and a candidate will take the GOP nomination.

-- In the Sunshine State, Republicans face yet another must-win state for one candidate. Iowa was Mike Huckabee's Waterloo, as was New Hampshire for John McCain, Michigan for Mitt Romney and South Carolina for Fred Thompson. Only Thompson has lost so far, though given polls, tonight might be the end for Rudy Giuliani, who has staked his claim on a state that doesn't seem to be breaking his way. The final RCP Florida Average has Giuliani trailing McCain and Romney by just under 15 points. Asked by reporters yesterday if a loss would end his campaign, Giuliani exhibited a rare moment of doubt: "Wednesday morning, we'll make a decision," he said, per AP's Libby Quaid.

-- McCain and Romney are locked in a pitched battle. not only for Florida but for first place in the race as a whole. In recent days, McCain has called Romney a flip-flopper and accused him of setting a time-table for withdrawal in Iraq. Romney has pushed back hard, calling McCain dishonest and accusing him of hidden liberal tendencies. The winner of that argument looks likely to win the nomination. The two candidates, both of whom have their problems with the Republican base, look like finalists for the job. Given Thompson and Huckabee, one of whom is out and another who looks on his way out, is it really the case that conservatives didn't have a candidate, or did they have a candidate and choose McCain and Romney in spite of that choice?

-- Given the fact that Romney has run almost ten times as many advertisements as McCain, should he be worried that he remains fractionally behind? Romney, as Ambinder writes, ran more ads in September than McCain has run to date, and McCain's lead can be seen in one of two lights: First, McCain, media darling and noted maverick, is ahead despite his lack of money through sheer force of will and the advantage of running eight years ago gives him an insurmountable head start. Second, Romney, unknown outside Massachusetts and Utah when this thing started, has come within an inch of overtaking a war hero with previous presidential race experience while far outpacing America's Mayor. Either way, both candidates look pretty good coming out of Florida.

-- While there's no love lost between McCain and Romney, there doesn't seem to be any affection between Hillary Clinton and Barack Obama as well. Even as Clinton shook Ted Kennedy's hand at last night's speech, Obama refused to offer his own hand, Frank James writes at The Swamp. It was the first time the two have seen the inside of the chamber in which they ostensibly work, during votes on FISA, and each had several opportunities to say hello to the other. As far as reporters know, neither took advantage of those chances.

-- Indicative of the keys to a Clinton win: She's bought time on Spanish-language radio networks. After her Nevada performance, and Obama's big win among African Americans in South Carolina, Clinton is depending on her enduring popularity among Hispanics for another win. But, perhaps indicative of how tenuous that strategy seems, according to Politico's Ben Smith: That Spanish-language radio buy is going into Clinton's home state of New York. The district to watch: That of Clinton backer Rep. Charlie Rangel, based in Harlem, which is 31% African American and 48% Hispanic.

-- Rankings Of The Day: Ted Kennedy's decision to back Obama at a mega-rally yesterday in Washington dominated cable news nets as much if not more than Bush's speech. That's because his was a Symbolic Endorsement, the highest level in the endorsement hierarchy, Chris Cillizza writes. Below the Symoblic, a candidate can score a State-Specific (Statewide) Endorsement, a Celebrity Endorsement, State-Specific (Non-Statewide) and the Pariah Endorsement (say, the New York Times in a GOP primary). Off the top of our head, we can't think of anyone other than Al Gore who remains in the Symbolic Endorsement category.

-- Today On The Trail: Republicans are tracking down last minute votes in Florida: Giuliani's in Miami Beach, Pompano Beach, Del Ray Beach and Orlando. McCain, to be accompanied by Gov. Charlie Crist, hits polling places in St. Petersburg before hosting a party in Miami. Romney holds his final event in Tampa before an election night party in St. Pete. Only Huckabee is out of state, stopping by a Tampa polling station before heading to Jefferson City, Missouri, as well as a fundraiser in St. Louis. Edwards kicks off his day in Tulsa before heading to Jefferson City, Missouri and St. Paul, Minnesota. Obama's back in El Dorado, Kansas, where his grandparents lived, followed by a town hall meeting in Kansas City, and Clinton heads to Florida to thank her supporters after polls close.