KANSAS CITY, Mo. -- State Auditor Claire McCaskill will announce her candidacy for governor Monday, ending months of speculation on whether she would run against Gov. Bob Holden in next year's Democratic primary.

McCaskill will officially open Missouri's first primary challenge to an incumbent governor since 1980 when she holds a news conference Monday morning at the Jackson County Courthouse, her campaign staff said Friday in a news release. Later in the day she will repeat the announcement in Columbia and St. Louis.

Elected last year to a second term as auditor, McCaskill -- a former state legislator and two-term Jackson County prosecutor -- has long been candid about her plans to seek the Democratic nomination for governor someday.

Until this year, however, those plans had not included a showdown with a Democratic incumbent seeking a second term.

Last October, shortly before her re-election as auditor, McCaskill told reporters it was "my intention to run for governor in 2008." And in a 2001 interview, she said, "I would never run against Bob Holden in a Democratic primary and I don't think anyone would be wise to do that."

But McCaskill, 50, backed away from that pledge in recent months as some Democrats worried that Holden could be vulnerable in November 2004 because of the poor economy, the state's budget troubles and his owned mixed fortunes with the Republican-controlled legislature.

McCaskill has been raising money for several months for an unspecified campaign, and her chief spokesman in the auditor's office left that job last month to become interim manager of the St. Louis-based "Friends of Claire" campaign staff.

In a campaign finance report filed Wednesday, McCaskill reported having more than $1.3 million on hand after raising more than $414,500 -- including nearly $130,000 from a personal loan -- from July through September.

Holden's campaign raised $470,284 in the same period, with more than $2.3 million on hand, according to its report to the Missouri Ethics Commission.

Meanwhile, the expected Republican nominee -- Secretary of State Matt Blunt -- reported raising nearly $514,000 from July through September and had over $1.2 million cash on hand at the end of the period. No other candidate for the GOP nomination has come forward so far.

Holden and McCaskill both began their political careers in 1982, when both were elected to the Missouri House and served four terms. In 1989, Holden joined U.S. Rep. Dick Gephardt's staff in St. Louis and McCaskill went to work for a Kansas City law firm.

McCaskill served on the Jackson County Legislature in 1991-1992, then won the first of two terms as county prosecutor.

Although there was speculation that McCaskill would run for the open governorship in 2000, she chose instead to run in 1998 for state auditor.

The position had been held by accountants since 1974, which was the last year the office was occupied by a non-accountant -- Republican John Ashcroft, who went on to become Missouri attorney general, two-term governor, U.S. senator and now attorney general of the United States.

Missourians last had the chance to oust an incumbent governor in a primary election in 1980, when then-state Treasurer James Spainhower challenged Democratic Gov. Joseph Teasdale.

Teasdale won his party's primary but lost in the general election to Republican Kit Bond, whom Teasdale had ousted from the governor's office four years earlier.

McCaskill's news conferences Monday are scheduled for 9:30 a.m. in Kansas City at the Jackson County Courthouse, where she worked as county prosecutor; 12:30 p.m. in Columbia at Hickman High School, her alma mater; and at 3:30 p.m. in St. Louis at Chase Park Plaza, 232 N. Kingshighway.