In just a few more days, American voters will determine who will win control of the Senate during the Midterm Election.

More than likely, the Republican Party will maintain control of the House of Representatives. However, the GOP only needs to pick up six senatorial seats in order to also win control of the upper chamber, which political experts predict will come down to hotly contested races in several states.

One state is New Hampshire, where Republicans are continuing to spend a lot of money on ads in the last few days before Election Day. Another state is Alaska, but it is hard to predict in which direction the voters will swing.

Other states include Louisiana and Georgia, which may result in runoff voting in either December or January.

"We have it between eight and 10 campaigns that are on a razor's edge,'' said Rob Collins, executive director of the Republicans' Senate campaign arm, according to the Wall Street Journal.

Likewise, Guy Cecil, of the Democrats' Senate campaign committee, said the party's own polling showed that "in the top-10 races in this cycle, we are within the margin of error."

"We think it's very, very tight," said Steven Law, president of Crossroads. "We also think it's important to do everything we can to have a good showing out of the urban areas, because we are a little concerned about the ground game" in rural areas, where Democrats are making significant efforts to turn out supporters, some of them in remote communities.

However, Democrats have an advantage being that history shows that voters tend to re-elect Democratic incumbents. After unseating a dozen Democratic senators in 1980, the Republican Party has since failed to beat more than two sitting Democrats in a single two-year election cycle.

"Incumbents are really hard to beat," admitted Collins, of the National Republican Senatorial Committee.