Sen. Sam Brownback, a favorite of social conservatives, announced Monday that he was taking the first step toward a 2008 White House run by setting up an exploratory committee.
"I have decided, after much prayerful consideration, to consider a bid for the Republican nomination for the presidency," the Kansas senator said in a statement.
"There is a real need in our country to rebuild the family and renew our culture, and there is a need for genuine conservatism and real compassion in the national discussion."
The 50-year-old Brownback is a leading opponent of abortion rights, embryonic stem-cell research and gay marriage. He also is generally opposed to the death penalty and has made alleviating disease and poverty in the developing world a cornerstone of his Senate work.
In his news release, he called for a flat tax, term limits for judges and members of Congress, and "compassionate yet practical programs to help the poor here and around the world."
The formation of a committee allows Brownback to begin raising money and test support for a presidential race without making a formal commitment to seek the nomination.
Sen. John McCain, R-Ariz., and former New York Mayor Rudolph Giuliani already have such groups, but neither GOP hopeful has wide appeal among conservatives.