In the 2010 midterm elections, a wave of Republicans surged into the 112th Congress, consolidating the GOP hold on the House of Representatives. Although the Republican onslaught is unlikely to be repeated, this year’s midterm elections may shift the balance in the Senate, where the GOP is expecting to capture the majority.

Historically, midterm elections tend to reflect public attitudes toward the incumbent president. According to an NBC News/Wall Street Journal poll conducted Sept. 3–7 by Hart Research Associates (D) and Public Opinion Strategies (R), more than half (54 percent) of those surveyed disapprove of the job President Obama is doing. “The combination of an unpopular president and a midterm election (indeed, a second midterm) can produce disastrous results for the president’s party,” wrote political pollster Stu Rothenberg in an article for Roll Call.

Indeed, with many voters still critical of the healthcare law, the economy generally, and most recently, foreign policy, Democrats are bracing for an ugly midterm election. That has Rothenberg believing Republicans may gain at least seven Senate seats. Specifically, open seats that previously had Democratic Senators in West Virginia, Montana, and South Dakota are all expected to go to Republican candidates.

In addition to winning the three open seats, however, Republicans would need to win a net of three more seats to become the Senate majority. That may be more difficult to accomplish, because candidates will have to beat current incumbents. According to Roll Call, at least four Democratic Senate incumbents are facing difficult races: Louisiana’s Mary Landrieu (against Rep. Bill Cassidy, MD), Arkansas’ Mark Pryor (against Rep. Tom Cotton), Alaska’s Mark Begich (against Dan Sullivan), and North Carolina’s Kay Hagan (against State Rep. Thom Tillis). If polls were held on October 15, Louisiana, Arkansas, and Alaska would all gain Republican Senators. This would give Republicans the Senate majority, 51-49, but a curious Senate race in Kansas may throw a wrench into the plans.

Senator Pat Roberts (R) of Kansas, elected to the Senate in 1997, is currently battling to keep his seat from an Independent candidate named Greg Orman, a Kansas business man. Independents in the Senate are not uncommon, both Senators Angus King of Maine and Bernie Sanders of Vermont caucus with Democrats, but no one knows who Orman would caucus with, should he be elected. Some believe he would caucus with Republicans because of comments he has made in recent debates, like lowering corporate tax rates, cutting abuse of social security disability payments, and cutting social welfare spending to help the Highway Trust Fund. Conservatives are skeptical; in early September the Democratic Party of Kansas forced their candidate to pull out, leaving Orman as the only non-Republican candidate, and also leading some to believe Orman’s “No Labels” candidacy is a façade. Currently, Orman is leading Sen. Roberts by one point. Should Orman be elected, a party-line vote in the Senate would be 50-50.

House races have received less national media attention; most analysts agree that Republicans will expand their 17-seat House majority by anywhere from two to 12 seats. As of October 15 polling, Republicans could gain six seats in the Senate.

This post was authored by Elizbeth Fassbender, Washington, D.C.