(CNN) - Business before politics - that's the message from Rudy Giuliani.
The former New York City mayor announced Tuesday that he won't run for either governor or the U.S. Senate next year in New York. Instead, Giuliani says he'll concentrate on his lucrative law office and consulting business. But the 2008 GOP presidential candidate wouldn't rule out a future run for office.
"The main reason has to do with my two enterprises, Bracewell-Giuliani and Giuliani Partners. I'm very busy with both," Giuliani told reporters in New York City. "We have some pretty significant commitments next year that will really make it impossible for me to run full time for office."
Giuliani also endorsed fellow Republican Rick Lazio for governor of New York. Lazio, a former congressman from Long Island who announced his candidacy for governor in September, joined Giuliani at the news conference.
Giuliani's public endorsement of Lazio was a formal declaration that he is not running for governor. The New York Times reported last month that he had decided not to run, but a spokeswoman for Giuliani said he had not made up his mind. At the time, polls indicated that Giuliani had a wide lead over Lazio in a hypothetical 2010 GOP primary contest.
Lazio deferred to Giuliani in the 2000 Senate race against then-first lady Hillary Clinton. Giuliani dropped out of the contest five months before the election, due to his fight against prostate cancer. Lazio replaced him as the Republican candidate, but lost to Clinton.
Recent polls of New York State voters suggest the race between Lazio and Democratic Gov. David Paterson is deadlocked, but the surveys indicate that the Republican trails far behind New York Attorney General Andrew Cuomo in a hypothetical general election matchup. Cuomo ha not said whether he'll challenge Paterson in the Democratic primary.
There was speculation that if Giuliani decided against a run for governor, he might consider launching a Senate bid. Top New York Republicans had reportedly urged Giuliani to run for the Senate next year.
Two recent polls indicated that Giuliani led Democratic Sen. Kirsten Gillibrand, the upstate congresswoman serving as Hillary Clinton's Senate replacement, by double digits in a possible 2010 showdown.
Giuliani said Tuesday that he had considered 2010 runs for either governor or senator.
"At different times, I thought about both races, and at different times I thought I might do it," said Giuliani. "I would have enjoyed running for either office, but it just isn't the right time."
Giuliani says he wants to help campaign for Lazio in next year's gubernatorial battle in New York and added that he will also campaign for other Republicans in the Empire State as well as other races around the country.
"I will be very active to the extent that I can in the races in Florida, where (Florida Attorney General) Bill McCollum is running (for governor) and Texas, where Governor (Rick) Perry, who was very very good to me when I ran, is running, and then a number of other races here in the northeast," said Giuliani.
As for another run for the White House, Giuliani said he wouldn't rule anything out.
"I have no idea whether I'll run for something else," said Giuliani.