JEFFERSON CITY, Mo. -- Gov. Matt Blunt says he simply lost his sense of mission. That's the best, and essentially only, explanation he is providing for why he will not seek re-election this year.

Blunt insists he could have won if he had decided to run. And the Republican governor says criticism over Medicaid cuts and alleged e-mail destruction in his office had nothing to do with his exit from politics.

At a Capitol news conference Wednesday, Blunt declared he was "absolutely at peace" with his decision and has no intention of resigning before his term ends January 2009.

"I didn't feel that sense of mission," Blunt told reporters repeatedly probing for insight into his decision.

Blunt said much the same thing in a videotaped statement released Tuesday in which he first revealed he would not seek re-election. The announcement stunned allies and enemies alike and sent Republicans into an immediate scramble to come up with a replacement.

On Wednesday, Blunt declined to endorse any of the numerous Republicans deciding whether to enter the race.

As it stands, Democratic Attorney General Jay Nixon is the only major candidate still running for governor. Nixon vowed to press forward during a Capitol news conference with dozens of Democratic lawmakers united behind him.

Blunt's announcement came just one week after he delivered a State of the State address highlighting his accomplishments and outlining his priorities for the year. Blunt said he decided not to run again sometime after that speech, after several days of careful consideration and prayer.

Blunt also cited a desire to spend more time with his wife, Melanie, and their son, Branch, who is almost 3 years old.

But he gave no indication of what he intends to do upon leaving office in January 2009.

Though he had never formally announced a re-election campaign, Blunt had raised millions of dollars for his 2008 gubernatorial committee and sparred frequently with Nixon. No other Republicans had entered the governor's race, assuming the well-financed Blunt made for too stiff of a challenge.

Within hours of Blunt's announcement, Republican Lt. Gov. Peter Kinder issued a statement pledging to formally announce his gubernatorial plans within weeks and proclaiming, "I am the right person to deliver the positive change Missourians deserve."

State Treasurer Sarah Steelman, who had announced her own re-election bid just hours before Blunt's stunning announcement, said Wednesday that she now is considering whether to run for governor and will announce a decision soon.

Others Republicans considering the gubernatorial race included former U.S. Sen. Jim Talent; U.S. Attorney Catherine Hanaway; U.S. Rep. Jo Ann Emerson; House Speaker Rod Jetton; and former state Rep. Jack Jackson.

A spokesman for U.S. Rep. Kenny Hulshof, who seriously considered a gubernatorial bid in 2004 before deferring to Blunt, said Hulshof was surprised at Blunt's announcement but gave no indication about his intentions.

Political scientist David Webber said Blunt's departure would create "a distraction for the Republicans" until the state's August primary elections, especially if no front-runner quickly emerges. That should give Nixon a boost but may not automatically propel him into office.

"I don't think there's a big vacuum," Webber said. "I think that the Republicans do have a strong party organization and they have experienced candidates, so it shouldn't be hard for them."

The son of U.S. Rep. Roy Blunt, Matt Blunt was the second-youngest Missouri governor when in January 2004 he ushered in the state's first Republican-controlled Legislature and Governor's Mansion in about 80 years. He had served the four previous years as secretary of state and before that spent just one term as a state representative from southwest Missouri, from 1999-2001.

The Republican Legislature passed almost every priority Blunt backed.

Among them: restrictions on liability lawsuits; a new school funding method; economic development incentives; tougher penalties on child sex offenders; an ethanol mandate for gasoline; abortion restrictions; and a new college scholarship and construction plan.

But Nixon had made Blunt's 2005 Medicaid cuts the central point of his campaign.

A poll conducted in November for the St. Louis Post-Dispatch and TV station KMOV showed Nixon ahead of Blunt, 51 percent to 42 percent, with a margin of error of plus or minus 3.5 percentage points. It also revealed that 57 percent of the 800 likely voters polled by Research 2000 opposed Blunt's handling of health care, and 61 percent said Blunt's handling of health care would be an important, or very important, factor in deciding their vote for governor.

Blunt had built a fundraising advantage over Nixon. Last week, Blunt reported $4 million on hand compared with Nixon's $1.7 million. But Blunt still needed to refund more than $2.3 million of that to comply with a Missouri Supreme Court ruling that reinstated campaign contribution limits.