"Despite remarkable success at building financial and organizational support for a campaign, I am convinced that a statewide campaign would be a distraction from finishing the work New Jersey voters had asked me to complete," Whitman said in a prepared statement.
Two sources told CBS News Whitman's decision had nothing to do with her health. The sources said Whitman and her family decided on vacation that raising the huge amount of money it would take plus anticipated conservative opposition by talk show host Bob Grant made the contest unappetizing to her.
There has been speculation that Whitman would make herself available for a possible GOP vice presidential pick, but the sources said they believe that she is too liberal for a Republican "moderate" like Texas Gov. George W. Bush, the front-runner for the GOP presidential nomination.
Whitman's departure opens a free-for-all on the Republican side of next year's race to succeed Democrat Frank Lautenberg, who is leaving the Senate after three terms. With Whitman's stature casting a long shadow, the only other candidate to enter the GOP race until now was former Libertarian gubernatorial candidate Murray Sabrin.
Candidates on the Democratic side include Corzine, former state party chairman Tom Byrne and former Gov. Jim Florio, whom Whitman ousted from the Statehouse in 1993.
After months of consideration, Whitman in April formed a fundraising committee and declared her intent to run for Senate.
"I believe I can contribute a great deal for the state of New Jersey in the United States Senate," Whitman said at the time.
Her fundraising operation got off to a quick start, raising more than $1.25 million in the first six months of this year.
Whitman, barred by law from seeking a third term as governor, started raising money for the campaign but never officially entered the race.
The New Jersey seat is important to both parties, as Republicans try to maintain their Senate majority in 2000.
Whitman ran for the Senate in 1990, her first statewide race. She nearly beat heavily financed Democratic incumbent Bill Bradley in a campaign that targeted Democratic Gov. Jim Florio's tax increases. Three years later, Whitman used that argument to defeat Florio.
Whitman gained national prominence for her tax cuts, and fended off persistent speculation that she was on vice presidential short lists during her first term. She then had to survive a surprisingly close race for re-election in 1997, when Democrat Jim McGreevey targeted the state's high auto insurance rates and property taxes.
She is a social moderate who supports abortion rights, something that may hurt her on the national stage but is considered an asset in a Senate run in New Jersey.
©1999 CBS Worldwide Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report