markudall-091814.jpg Incumbent Colorado Sen. Mark Udall, D-Col., trails his Republican challenger in the latest Quinnipiac University poll, with more than a third of likely voters describing their U.S. Senate vote as a vote against President Barack Obama.

joni-braley-091714.jpg Republican Joni Ernst has moved into the lead in the potentially crucial Iowa Senate race, according to the results of a Quinnipiac University poll released on Wednesday. The poll found that 50 percent of likely Iowa voters would support Ernst if the election were held today, while 44 percent would vote for Democratic Rep. Bruce Braley.

Jeanne-Brown-091514.jpg In a race that could potentially play a big role in determining which party controls the Senate, the results of a CNN/ORC International poll showed incumbent New Hampshire Sen. Jeanne Shaheen, D-N.H., running neck-and-neck with Republican challenger Scott Brown.