A new Brown University poll shows Republican Sen. Lincoln Chafee and Democratic challenger Sheldon Whitehouse neck-and-neck two months before an election that could help decide the balance of power in the U.S. Senate.

If the election were held Tuesday, 40 percent of voters said they would select Whitehouse, compared to 39 percent for Chafee.

That lead is negligible because the poll, conducted between Sept. 16-18, questioned 578 likely voters and has a margin of error of plus or minus 4 percentage points.

Rhode Island's Senate race is particularly heated this year because Republicans hold a slim majority in the U.S. Senate. Democrats are trying to close the gap and they view Chafee, a moderate Republican, as vulnerable in a heavily Democratic state.

Whitehouse has enjoyed a relatively easy run so far, defeating two lesser-known challengers in the Democratic primary. He sat on the sidelines while Chafee fought off a primary challenge from Cranston Mayor Stephen Laffey, a social conservative.

Republican Gov. Don Carcieri has opened up a lead over his Democratic challenger, Lt. Gov. Charles Fogarty, according to the poll. Almost half of those polled chose Carcieri, compared to 38 percent for Fogarty.