WASHINGTON (MCT) — President Barack Obama appears to have made progress with his efforts to seed doubts among voters about Mitt Romney’s background, a new national poll shows.

The survey by the independent Pew Research Center found that more than one in three registered voters would like to learn more about Romney’s record as a buyout executive at Bain Capital, his service as Massachusetts governor and his income tax returns. All have been the object of continuing attacks by Obama, propelled by campaign ads in battleground states.