Mitt Romney's senior campaign adviser in Florida hinted on Thursday that the Republican presidential challenger lost the state, where a result was still to be declared two days after the election, AFP reported.

President Barack Obama ended up not needing the biggest swing state as he romped to a decisive electoral college victory on Tuesday.

A statement from Romney's Florida campaign published in the Miami Herald and quoted by AFP suggested his team had already accepted defeat.

"The numbers in Florida show this was winnable. We thought based on our polling and range of organization that we had done what we needed to win," senior campaign adviser Brett Doster said in the statement.

"Obviously, we didn't, and for that I and every other operative in Florida has a sick feeling that we left something on the table," he said.

Meanwhile, Obama campaign manager Jim Messina said he was confident the president would be declared the victor.

"Sometime today (Thursday) we think we will officially be the winner in Florida," Messina said, according to AFP.

The campaign's voter model continues to show that Obama "will hold that lead and end with 332 electoral votes," Messina said.

270 electoral votes were needed for victory and Obama already has 303 with Florida's 29 still outstanding.

Votes are still being counted in three of Florida's 67 counties, said Chris Cate, a spokesman for the state government. "Counties are required to report their results to us by Saturday at noon," Cate told AFP.

As the results of the election came in on Tuesday night, Romney at first would not concede to Obama, saying he did not agree with the declaration that the president had won the swing state of Ohio.

Eventually, however, Romney conceded the election to Obama. The popular vote difference across the U.S. was only an insignificant 0.3%, reported Fox News, a number which probably would have resulted in a recount if not for the electoral college system.