Washington ? Sen. Sam Brownback, a Kansas Republican and favorite son of the religious right, will officially enter the presidential race later this month in his home state.

“He will be fully announcing on January 20 in Topeka, Kansas,” Brian Hart, the senator’s spokesman, said Friday. The move was expected even though Brownback set up an exploratory committee in December to gauge whether he had enough support for a full-blown campaign.

After the announcement in Kansas, Hart said Brownback will fly to Washington to participate in the anti-abortion march marking the anniversary of the Supreme Court ruling.

Brownback is a lesser-known candidate in a crowded GOP presidential field that likely will include Sen. John McCain, R-Ariz., and Rudy Giuliani, the former New York City mayor. Mitt Romney, the former Massachusetts governor, rounds out the top tier. All three are considering runs but, to various extents, also have records or positions on social or fiscal issues that don’t sit well with the Republican base.

So, Brownback – a Catholic revered by the GOP’s conservative wing for his opposition to abortion and gay marriage – sees an opening in the race for someone like him. “I am an economic, a fiscal, a social and a compassionate conservative,” Brownback said last month.

At the time, Brownback also called for a return to an American culture that promotes family values. He said the main focus of his campaign would be “to save and improve lives, rebuild families and renew the culture” in the United States that supports the institution of family.

Brownback, 50, was raised on a farm near tiny Parker, Kan. – population 281 today – where his parents still live.

His first foray into national politics was in 1976 while a student at Kansas State University, where he campaigned for Ronald Reagan in his unsuccessful quest to wrest the GOP nomination from Gerald Ford.

After receiving his law degree from Kansas University in 1982, he practiced law in Manhattan, Kan., and served as secretary of the state board of agriculture. He was named a White House fellow in 1990, and worked in the office of the U.S. trade representative.

Brownback was elected to the House in 1994, part of the Republican revolution that gave the GOP control of both the House and Senate for the first time in 40 years.

Two years later, Brownback was elected to the Senate, winning the seat Bob Dole vacated to run for the presidency. Brownback, who promised to serve no more than two terms, has said he will not seek re-election in 2010.