"We will be successful, not because of who the Republicans nominate, but because Missourians know that change will only happen if we elect a governor with fundamentally different priorities," Nixon said.
Nixon reiterated his campaign's major themes of restoring health care cuts, creating more jobs and lowering the cost of education.
Nixon's press conference in the Capitol followed Gov. Matt Blunt's on Wednesday morning, during which Blunt said he believed he had achieved all of the goals he set out to accomplish four years ago.
When asked whether he felt his resignation might hurt Republican chances to retain the governor's mansion, Blunt said he felt the Democrats will have more trouble responding to the change.
"I think the people in a poor situation are the folks on the other side that have spent three years running against the candidate," Blunt said.
Who that candidate may be is now the question. State Treasurer Sarah Steelman announced Wednesday that she would seek another term in her current office, but she now says she is considering running for governor after receiving support from constituents.
"We will be announcing our decision soon so as to help lead Missourians in the best possible direction," Steelman said in a statement Wednesday afternoon.
On Tuesday, Lieutenant Governor Peter Kinder released a statement setting a timetable for an announcement on whether he will seek the governor's office in the next couple weeks.
Other possible candidates mentioned by the St. Louis Post-Dispatch on Wednesday were U.S. Representatives Jo Ann Emerson, Sam Graves and Kenny Hulshof; U.S. Attorney Catherine Hanaway; Missouri House Speaker Rod Jetton and former Sen. Jim Talent.
Blunt has declined to endorse a Republican candidate at this time.
Missouri Democratic Party spokesman Jack Cardetti said the Republican candidate, whomever it is, will echo the governor's positions on health care, the economy and education.
"The contrast on important issues couldn't be more clear," Cardetti said.
Democratic Floor Leader Paul LeVota, D-Jackson County, said Republicans are unclear as to who their standard bearer is and what their message is, while House Democrats are united around Jay Nixon and his agenda.