Salt Lake County Mayor Peter Corroon, who has been urged for months by Democratic faithful to join the race, plans to announce next week that he will run for governor, The Salt Lake Tribune has learned.

Corroon is expected to announce his candidacy Tuesday at Salt Lake Community College, several Democratic sources familiar with the plan told The Tribune .

The sources spoke on condition of anonymity, since they were not authorized by the campaign to discuss Corroon's intentions.

Corroon did not respond Thursday to requests for comment.

Corroon's entry into the race, while not a surprise, gives Democrats one of their strongest possible candidates to challenge Gov. Gary Herbert, who inherited the office in August when Gov. Jon Huntsman Jr. became U.S. ambassador to China.

The two-term county mayor cruised to re-election in 2008 and is generally viewed as politically moderate. He is expected to remain in office while he runs for governor.

A Herbert spokeswoman declined to comment until Corroon makes his announcement.

Corroon's candidacy would represent a rapid political rise for the soft-spoken Democrat, whom party insiders considered a long shot -- and even a "sacrificial lamb" -- when he ran for mayor six years ago.

But Corroon has become a household name in Utah's most-populous county, burnishing his reputation as a fiscal conservative through his high-profile rejection of a Real Salt Lake soccer stadium deal and as a reformer by returning stability to a county rocked by scandals that toppled his Republican predecessor.

Question is, will Corroon stand a chance in a statewide race? Utahns have not elected a Democratic governor since 1980.

"Obviously, because he's an elected official in the largest county in the state, that brings a lot of credibility to the race," said Matthew Burbank, a political science professor at the University of Utah.

But Burbank said Corroon still faces a tough fight to break through in Republican-dominated Utah.

"The problem he has is that, unlike Gary Herbert, he's not all that well known outside of Salt Lake County," Burbank said. "How he would play in Utah County or Davis County or Washington County remains to be seen."

Corroon also enters the race with a potential handicap: a tax increase on his record.

Although the mayor went toe to toe with the Democrat-led County Council last summer to defeat a proposed property-tax hike in the first veto of his administration, he later supported an increase to balance the 2010 budget, arguing further cuts could cripple critical services.

And Corroon, who has sworn off seeking a third term as mayor, has hard decisions left to make. He is a part of the county's three-member law-enforcement district board that will decide Monday whether to impose a $13 million police fee on unincorporated areas.

The mayor stood behind his actions in this week's State of the County address, saying, "we made these decisions because they were fiscally responsible and still protect vital services." While taxes will go up, the mayor said the county has slashed a record $142 million from its spending plan, reduced the size and salaries of its work force and still maintained its coveted triple-A bond rating.

Corroon now faces an incumbent governor, who, according to Burbank, has not done anything that would "ruffle feathers."

Herbert also has piled up more than $1.3 million in campaign contributions since taking office in August, including nearly $1 million raised in a single night during his annual fall gala.

Corroon has been raising money for the past several months through his Corroon Leadership Political Action Committee and is expected to have amassed several hundred thousand dollars when he files his disclosure Monday, sources said.

Utah Republican Party Chairman Dave Hansen said he's not surprised Corroon will get into the race, but predicted a Herbert victory.

"You have to take every challenge as a tough challenge, but the simple fact is that Gary Herbert has done an excellent job," Hansen said. "As campaigns involving an incumbent are, this is more of a judgment on the job that Gary Herbert is doing, not a contest between two people, and that's why Gary Herbert will be re-elected in 2010."

However, Salt Lake County Democratic Party Chairman Weston Clark sees a promising contest. He said the party will have his back in winning a county that is "extraordinarily important" to Corroon's success.

"We are going to need every vote we can get in Salt Lake County to counteract the Republican machine outside the county," he said. "We need Mayor Corroon to perform well."

The mayor's candidacy would delight Misty Fowler, who helped create the "Draft Peter Corroon for Governor in 2010" Facebook page that now has more than 1,100 followers. "Mayor Corroon will make an absolutely amazing governor," said Fowler, who added she and many of Corroon's Facebook followers would readily donate money and time to the campaign. "He will do what is best for the state of Utah, regardless of the politics of the decision."

gehrke@sltrib.com

jstettler@sltrib.com