A new poll shows Sen. Mary Landrieu, D-La., one of the most vulnerable incumbents seeking re-election in 2014, performing strongly against her likely Republican challenger, Rep. Bill Cassidy.

Landrieu polled at 50 percent in the PPP survey, with Cassidy at 40 percent.

The result contrasts slightly with two Republican polls released recently, including one commissioned by the National Republican Senatorial Committee, which showed Landrieu and Cassidy in a statistical dead heat.

But the Democratic-leaning PPP noted that many undecided voters disapprove of President Obama, and so Cassidy’s support will likely increase as the election cycle progresses.