A new Public Policy Polling survey shows that Sen. Richard Burr's (R-N.C.) fortunes have not improved much, and that early in the cycle, he could be vulnerable to a strong Democratic challenger.

Burr's approval rating held steady at 35 percent in the survey, with 31 percent disapproving (down 1 point from 32 percent in a March survey). This month's poll also tested two potential Democratic challengers: Attorney General Roy Cooper (D), who has a fav/unfav rating of 41/20, and Rep. Mike McIntyre (23/21).

A March survey showed Burr leading 42-38% over a generic Democratic candidate. Here's how Burr fared against these Democrats:

General Election Matchups
Cooper 41
Burr 37
Undecided 22

Burr 39
McIntyre 34
Undecided 27

Burr fails to reach the critical 50% threshold for incumbents even against McIntyre, a 7-term Congressman representing the southern part of the state. Democrats are hoping to recruit Cooper, who was elected for a third time to the statewide office last fall.

Former Sen. Elizabeth Dole (R) showed similarly weak numbers throughout her final years in office, but high profile Democrats passed on the race. But the little-known state Sen. Kay Hagan (D) was able to mount a strong challenge, and easily defeated Dole in 2008 in a state that Barack Obama also carried.

The PPP survey was conducted April 8-11, and had a margin of error of +/- 3.1 percent.