WASHINGTON - The shadow campaign between Newark, N.J., Mayor Cory Booker and U.S. Sen. Frank Lautenberg just went into full swing, even if the real matchup may never happen.

Neither Democrat has officially said whether he will run in 2014, when Lautenberg's Senate term ends, but reports and rumors flew Friday after Booker filed papers moving him closer to an expected campaign.

A report from WNBC-TV in New York City said Lautenberg, who turns 89 this month, had decided not to seek another term, but a spokesman for the senator quickly denied that.

"The news report that claims Sen. Lautenberg has decided to retire is simply not true," spokesman Caley Gray said. He said Lautenberg had not decided either way.

The original report cited unnamed sources said to be familiar with Lautenberg's thinking. While one source relayed similar information to The Inquirer, several other New Jersey political insiders said there had been no word from Lautenberg.

The stir came hours after news broke that Booker had filed papers to create a Cory Booker for Senate campaign committee to run in for the seat Lautenberg holds. He filed the documents with the Federal Election Commission on Tuesday.

That step added steam to the widespread expectation that Booker will run for the Senate in 2014, though he could choose not to and has not announced a firm decision.

Booker filed the papers "to be prepared for a possible U.S. Senate campaign, but his focus remains on completing his vision for a revitalized Newark," said a statement from Booker political director Mark Matzen. "As part of the process of exploring a possible Senate run, the law requires any expenses in such an exploration to come from a federal account."

Few would be surprised if Lautenberg, who joined the Senate 30 years ago, chose to retire. He will turn 90 in 2014 and would be seeking another six-year term. Recent opinion polls consistently favor Booker.

But Lautenberg briefly retired once before from the Senate, hated it, and may not want to leave the impression that he has been pushed out. He has not publicly commented on his political future since Booker's December announcement that he was considering a 2014 run.

After the news that Booker had filed to create a campaign committee, an anonymous Lautenberg aide told Politico that the mayor "is self-absorbed and disrespectful."

The aide, described by the website as a "senior adviser" to Lautenberg, accused Booker of ducking a tough race against Gov. Christie this year in order to "take on a long-serving, loyal Democrat." Those were hardly the words of someone planning to quietly walk away, one New Jersey political insider said.

Lautenberg is said to be so angry with Booker that even if he retires, he might back another candidate against Booker in the Democratic primary, three sources said. Speculation has swirled around a possible run by U.S. Rep. Frank Pallone (D., N.J.).

The report about Lautenberg's plans came out on the same day that another senator, Jay Rockefeller (D., W. Va.), 75, announced he would not seek another term in 2014.

Whispers about Lautenberg's future will likely continue until he makes an announcement.

But none came on Friday, despite the churning political machinery.

Contact Jonathan Tamari at jtamari@phillynews.com or follow on Twitter @JonathanTamari. Read his blog 'Capitol Inq' at www.philly.com/CapitolInq.