Is Chris Christie preparing to run for president in 2012?

New Jersey Gov. Chris Christie has repeatedly denied that he intends to run for president in 2012, but according to Bloomberg View columnist Jonathan Alter, he is taking some early steps toward joining the race.

"My sources say NJ Gov. Chris Christie is conducting focus groups in preparation for a possible run for president in 2012," Alter wrote on Twitter just before 12:30 p.m. Eastern time on Wednesday.

(UPDATE: Alter now reports that another source close to the governor says there is no truth to the story. "Another source, close to Christie and v-reliable, says there are no Christie focus groups and nothing has changed," he posted on Twitter. "I trust him.")

Several high-profile Republicans have been calling on Christie to run for president for months, but every time he has been asked by the press, Christie has rejected the suggestion. Christie told reporters in November that there was "zero chance" he would run.

"Short of suicide, I don't really know what I'd have to do to convince you people that I'm not running," he said.

Of course, circumstances can change.

Republican strategist Karl Rove said Monday that he thinks Texas Gov. Rick Perry's decision to join the race could entice Christie to run.

UPDATE: The Washington Post's Jennifer Rubin reports that her sources within Christie's team say Alter's story is "absolutely not true."

A source tells CNN, though, that pressure on Christie to run has been "ratcheting up" since the Ames straw poll last weekend.

"I know he is getting a ton of calls and the pressure is ratcheting up, but as far as I know, his head is still where it's always been," the source told CNN.