Louisiana Senate

ASSOCIATED PRESS

Sen. Mary Landrieu (D) is a political survivor, having won her last three Senate races by narrow margins. She'll need another miracle if the nonpartisan primary on Nov. 4. goes to a Dec. 6. runoff, as all of the GOP's energy will presumably be focused on putting Rep. Bill Cassidy (R-La.) over the top, especially if control of Congress' upper chamber hinges on this race. Landrieu would need to significantly boost turnout in cities such as New Orleans to eke out a runoff win. Her brother is the mayor of New Orleans, though, so that could help.