Republican presidential nominee Mitt Romney is in a dead heat with President Barack Obama in three battleground states crucial to this fall's election, says a poll released Thursday.

The NBC News/Marist poll finds the candidates within statistical margins in support among registered voters surveyed in Iowa, Colorado and Nevada. In Iowa the two were tied at 44 percent. In Colorado, Obama held a 1-point edge, with 46 percent to Romney's 45. In Nevada, Obama led with 48 percent to 46.

Obama carried the three states in 2008, but according to the poll, trouble is emerging. The president will need to win half of the electoral votes in 12 battleground states he carried in 2008 to be reelected.

"These are very, very competitive states," Lee Miringoff, director of the Marist College Institute for Public Opinion, said in a statement. "Everything is close."

The result is good news for Romney, who clinched his party's nomination Tuesday night with a Texas primary victory, securing the 1,144 delegates needed to come out victorious at the GOP convention in Tampa, Fla. in August.

Perhaps more significantly was how voters view the candidates on their handling of the economy. Except for Nevada, where the candidates deadlocked on the matter, more voters in Iowa and Colorado see Romney as better prepared to handle the economy.

Political scientists and commentators have predicted the election will be about the economy, and both campaign have started to pummel the other camp on the issue.

Obama already has hit Romney hard on his tenure at the private equity firm Bain Capital, claiming he profited from shuttering American businesses.

Romney, meanwhile, countered by attacking the administration's failed loan guarantee for the bankrupt energy firm Solyndra. If the polls are any indication, for now, Romney has the upper hand in portraying himself as a "fixer" of the economy, while the Obama camp struggles to find a winning message on the economy.