By Bob Benenson, CQ Politics Editor

If the presidential contest between Democrat Barack Obama and Republican John McCain is very close, and the key races that will determine control of Congress are cliffhangers, then the wait for who won on Nov. 4 could be a long night’s journey into the next day — or, heaven forbid, into the next month, as in the nightmare Florida vote count of 2000. If Election Day produces clear-cut victories, then the winners will be living the high life and the losers drowning their sorrows well before midnight.

But if you’re the kind of person who wants to be the first to figure out which way Election Night is going to go — and if you’re reading CQ Politics, I’m guessing you are — then order those pizzas early and make sure you’re at that vote-watching party by 6 p.m. on Nov. 4. Starting out at 8 p.m. might be the equivalent of showing up for a baseball game in the fifth inning.

Fortunately for politics junkies, most of the states that will act as harbingers of how these elections will turn out are east of the Mississippi River, and several will close their polls (barring unexpected delays) between 6 p.m. and 7:30 p.m. eastern.

The states that will kick things off with the 6 o’clock poll closings are Indiana and Kentucky. In both cases, parts of each state are in the central time zone, so actual votes are unlikely to be reported until 7 p.m. eastern time. But the TV networks — though they have grown wary of blurting out the candidate match-up results from their exit polls — are likely to provide some of the demographic data from those early states that will provide clues to how close the Obama-McCain race is in those places.

Indiana, which has 11 electoral votes, is the one to watch more closely. This is a state that has gone Republican in 10 consecutive elections, and gave President Bush a whopping 60 percent to 39 percent victory over Democratic challenger John Kerry in 2004. But Obama, who represents the neighboring state of Illinois, made an early decision to heavily contest Indiana, and polls have shown him highly competitive against Arizona Sen. McCain. If the early returns were to show McCain receiving a much lower percentage than Bush did four years ago, it could be a sign of trouble for the GOP in other key “red” states where Obama is heavily competing, such as Florida, Virginia, North Carolina, Ohio, Colorado, Missouri and Nevada.

If it looks early on like Obama may actually win Indiana, the Democrats’ champagne-cork-popping fingers are going to get very itchy.

Obama has spent less time and money organizing in pursuit of the eight electoral votes in Kentucky, where McCain appears a more solid favorite. But here again, margin matters, so watch for how close the GOP nominee can come to Bush’s 60 percent vote share in 2004.

While CQ Politics’ ratings show that the Democrats are likely to make significant gains in both the Senate and the House, Kentucky and Indiana will give an early indication of how big those gains will be.

Democratic officials have set a very lofty goal of netting nine Senate seats, which would boost them from their current razor-thin de facto majority of 51 seats to at least 60 — the so-called filibuster-proof majority, because a three-fifths vote is needed to cut off delaying tactics on legislation. While CQ Politics currently rates the races for five Republican-held seats as leaning to Democratic takeover and four others as tossups, an upset or two would greatly help their cause. And one of their top targets is four-term Kentucky Sen. Mitch McConnell , the leader of the chamber’s Republican minority.

For most of the campaign year, McConnell looked relatively secure. But his lead over Democrat Bruce Lunsford, the wealthy owner of a chain of nursing homes, has shrunk in recent polls, which in turn has heightened the Democratic Senatorial Campaign Committee’s interest in the race. There are Democrats who have been eager to wage a full-scale effort against McConnell as revenge for the Republicans’ successful 2004 effort to oust South Dakota Sen. Tom Daschle, who at the time held the same minority leader position as the Kentucky incumbent does today.

The House contest in Indiana’s 3rd Congressional District will provide an early omen of whether the Democrats’ gains in that chamber will be modest or super-sized. Four years ago, the idea of a Democratic raid on this traditional Republican stronghold, which includes most of Fort Wayne: conservative GOP Rep. Mark Souder won his 2004 contest with 69 percent as district voters gave Bush 68 percent. But the national trend that has since been working against the Republicans, and Souder’s longstanding disinterest in the kind of full-time fundraising pursued by many of his House colleagues, contributed to his slip to 54 percent in his 2006 race. Democrats this year took a wait-and-see approach to their nominee, lawyer Michael Montagano, but recently added him to their list of priority challengers.

When 7 p.m. eastern rolls around, the polls will close in other 2004 Bush states that Obama is making all-out bids to turn Democratic blue — Virginia and all of Florida besides the Panhandle, which is on central time — and for his longer-shot bid in Georgia. The curtain will be pulled back at 7:30 p.m. in Ohio, where Bush clinched his re-election with a 2-point win over Kerry, and neighboring West Virginia, a traditional Democratic stronghold that Bush pulled away in 2000 and 2004 but where Obama, after initially appearing to write it off, has re-started his campaign late in the game.

If the early returns and exit polls show McCain weathering all of these state-by-state skirmishes, attention will turn at 8 p.m. to those states that gave Kerry narrow margins over Bush in 2004, such as Pennsylvania and Michigan. The election appears teetering to Obama, then it will add consequence the 8 p.m. eastern closing in Missouri, another state pursued by the Democratic nominee that went comfortably to Bush last time.