7 things that will almost definitely happen on Election Night

WASHINGTON (CNN) -- Happy Election Day, America. Things have changed since the last time everyone went to the polls. Then, Barack Obama was re-elected to a second four-year term. Now, he's been largely benched by his party, spending less time on the campaign trail. Midterm elections are more local affairs and the issues vary from contest to contest.

But midterms have national consequences, and what happens Tuesday will help determine what President Obama can get done in his final two years in office. It will tee up the coming 2016 presidential contest and give Americans the chance to try on a more powerful GOP as they start to think about who should be the next president.

But first comes Tuesday and here is what's going to happen:

#1 - There will be a surprise -- Something we're listing below won't end up happening. This is an election and it isn't over yet. Voters are fickle and polls aren't perfect and predictions are even less so.

#2 - Most Americans won't take part -- Most Americans won't have taken part in the election. Somewhere between 55% and 65% of eligible Americans vote in a presidential election (about 130 million people in 2012). Far fewer -- between 39% and 42% of Americans -- take part in a midterm election (about 90 million in 2010). Voter excitement is actually down from 2010, the last midterm election, according to the most recent CNN / ORC Poll.  Fewer than half the eligible population is likely to show up and let their voices be heard in this election.

#3 - Democrats will lose the Senate -- OK, this one is not a sure thing. And Vice President Joe Biden, at least, is still saying Democrats will keep their majority in the Senate on Tuesday. But all indications are that the GOP will gain seats and most likely enough for a slim Senate majority. Republicans need to gain six seats to win the majority in the Senate. There are three seats that were long-held by retiring or already retired Democrats in which a Republican is now heavily favored -- South Dakota, West Virginia and Montana. Among the rest of the races that CNN considers to be tossup or leaning toward the GOP, seven of them are held by Democrats. Just three are held by Republicans. Republicans have eaten away at Democrats' majority in each election since Democrats had a filibuster-proof majority when President Obama was first elected in 2008.

#4 - Republicans will elect an African American senator in the South -- Tim Scott is already a senator. He was appointed after South Carolina Sen. Jim DeMint retired from office to lead a GOP think tank. So it will be overlooked as an historical moment Tuesday night, but when he wins the race -- he is heavily favored -- Scott will become the first African American elected as a senator from the South and only the fifth African American elected to the Senate ever.

#5 -- There will be a runoff -- Two states with tight Senate races create the possibility for runoff contests. In both states, if no candidate gets more than 50% of the vote, the top two candidates head to a runoff. In both states there are three or more candidates and in neither state is any candidate getting more than 50% in recent polling. In Louisiana, the runoff would take place Dec. 6. In Georgia, the runoff would take place Jan. 6. Both races are extremely tight and with a slim Senate majority in the balance, it is possible to not know who controls the Senate for two months. But it bears mentioning the conventional wisdom that Republicans could do better in a two-person race on a non-traditional Election Day in those two southern states. In 2008, for instance, Sen. Saxby Chambliss got just shy of 50% on Election Day. In the December runoff, he got more than 57%.

#6 -- Not too much will change -- Yes, there might be a new Senate majority. Yes, Republicans will likely control both houses on Capitol Hill. They will control the schedule of the Senate floor and they'll control what hearings will be held in both the House and the Senate. It will be even more difficult for President Obama to get a potential Supreme Court nominee a confirmation vote if a vacancy should arise. But Democrats will still have well more than the 40 votes they'll need to block just about any legislation they want. If what angers you about Washington -- remember, voters are angry -- is that nothing seems to get done, this election isn't likely to make you very happy.

#7 -- It will be a nail-biter for incumbent governors -- There hasn't been a Democratic governor in Florida since 1999. So this year, Democrats ran a former Republican. The main storyline for Election Night has and will be control of the Senate, but there are a host of interesting governor's races and voters could send a strong message to incumbents and incumbent parties. Perhaps the closest and most interesting race of any kind is the Florida governor's race, where Republican-turned-Independent-turned-Democrat Charlie Crist is in the hunt to get his old job back with a new party. There are potential upsets brimming elsewhere. Republican Gov. Scott Walker is running neck-and-neck to to keep his job in Wisconsin. So is Democrat John Hickenlooper in Colorado and Republican Nathan Deal in Georgia. Polling is very dismal for Republican Gov. Tom Corbett in Pennsylvania and Paul LePage in Maine. It wouldn't be a total shock to see Republican governors in blue states like Maryland and Massachusetts and Democratic governors in red states like Kansas and Georgia.