Voters who could be asked to decide control of the Senate are beginning to make their selections, but some races remain competitive in what could be deciding states over who controls Congress. 

In Louisiana, the race between Democrat Sen. Mary Landrieu and Republican Rep. Bill Cassidy is likely to head into a runoff, according to a poll released this week that was commissioned by a group of television stations in the state. The runoff will likely come thanks to Republican Rob Maness, who is winning 6 percent of the electorate. He will likely prevent Landrieu, who is at 36 percent, or Cassidy, who is at 32 percent, from winning the needed 50 percent majority to ensure election. The poll also found that 23 percent remain undecided, so both candidates still have a chance to make inroads with voters before Election Day Nov. 4. 

With Republicans and Democrats battling fiercely around the country for control of the Senate, a runoff in Louisiana could make it the deciding state. While Landrieu is leading in the field of three candidates, the same poll found Cassidy in the lead when Maness is eliminated. In the head-to-head, Cassidy takes 43 percent of the vote compared to 40 percent for Landrieu, indicating a tight race. The poll of 605 registered voters has a margin of error of 4 percentage points.

In Kentucky, Democratic challenger Alison Lundergan Grimes is still running closely behind Senate Minority Leader Mitch McConnell. While most campaign watchers have already called the race for McConnell, Grimes has continued to poll closely with the minority leader. According to Western Kentucky University, Grimes is trailing McConnell by only 3.7 percentage points. McConnell remains the favorite at 45.4 percent of likely voters and Grimes is hodling on at 41.7 percent. Of the likely voters polled, 7.6 percent are undecided.

“A fascinating element of this campaign is the strong evidence of protest support among the candidates. Respondents were asked if they were voting for the candidate of their choice because they supported that candidate or opposed the opposition,” the poll reports. “The majority of those voting for McConnell (62 percent) indicated support for the Senator as their reason for voting for him. In contrast, the majority of those backing Grimes (60%) indicated opposition to McConnell as motivating their support for her.”

The poll also asked Kentucky voters to identify their most important issues on Election Day. In the WKU poll, 29 percent identified the economy, followed by jobs and international affairs, each identified by 17 percent of those polled. The poll of 601 registered voters has a margin of error of 4 percentage points.

Other polls released early this week show Senate candidates taking stronger leads in their races. In Arkansas, Republican Rep. Tom Cotton has an 8 percentage point lead over incumbent Democrat Sen. Mark Pryor, according to a poll by Talk Business and Politics. It is consistent with a series of recent polls showing Cotton holding on to a lead over Pryor. Arkansas is a piece of the map Republicans are banking on capturing to ensure their control of the Senate.

In Michigan, Democratic Rep. Gary Peters continues to hold a lead over Republican Terri Lynn Land. When Democratic Sen. Carl Levin announced he was retiring last year, Republicans were hopeful they could win the seat. However, Land, the Michigan secretary of state, has been unable to take the lead in the race. Peters holds a 13 percentage point lead over Land in a poll released late Monday by Fox 2 Detroit/Mitchell Poll. The lack of competition in the Senate race could have ramifications in the gubernatorial race, where Republican incumbent Gov. Rick Snyder leads by only 2 percentage points over Democrat Mark Schauer. The poll of 919 likely voters has a margin of error of 3.23 percentage points.

"We are picking up a tremendous amount of volatility in the United States Senate race,” Steve Mitchell, CEO of Mitchell Research & Communications, said in a news release. “Two weeks ago we had Peters up by only 2 percent; today we are showing him up by 13 percent."

In New Jersey, Sen. Cory Booker has a large lead over Republican challenger Jeff Bell. According to a poll by Fairleigh Dickinson University, Booker leads by 16 percentage points.