Topeka ? Conservatives are attacking moderate Republicans’ major stronghold in Kansas government, hoping voters in this year’s elections remove the last significant obstacles to Gov. Sam Brownback’s push to the right in policy.

A tide that washed over state politics in 2010, sweeping Brownback and fellow GOP conservatives into office, missed the state Senate, where only two seats were on the ballot in special elections. Anti-tax, small-government legislators and political activists buoyed by the rise of the tea party movement have been frustrated by Senate Republican leaders’ wariness toward the governor’s agenda, feeling it has hindered conservative gains.

But this year, all 40 Senate seats are on the ballot, and conservative candidates have emerged for potential Republican primaries in at least nine districts held by moderate Republicans. Those incumbents include President Steve Morris, of Hugoton; Vice President John Vratil, of Leawood; and budget committee Chairwoman Carolyn McGinn, of Sedgwick.

While Brownback is promising publicly not to get involved, groups that backed him are preparing to jump into contested races ahead of the August primary election. The governor also will be perceived as the beneficiary if moderates lose control over the Senate.

“There are many out there who believe the Senate is the final step,” said Derrick Sontag, state director for the anti-tax, small-government group Americans for Prosperity and husband of Brownback’s chief spokeswoman. “What it would do for Governor Brownback is that it would push him to the right. It would make his agenda even more conservative.”

Biggest game around

The state Senate races appear to be the year’s most politically compelling contests in Kansas. There’s no U.S. Senate race, statewide elected officials are in the middle of their four-year terms, and no serious challengers have yet emerged for the four members of the state’s all-GOP delegation in the U.S. House. Republican presidential caucuses in March could spark interest, but the state is expected to go for any Republican candidate in November, as it has since 1964.

Republicans have a 32-8 majority in the state Senate, and conservatives calculate that they’ll need a net gain of several seats to control the GOP caucus and choose the president and majority leader, who control the flow of legislation.

Conservative Republicans have led the House for most of the last two decades, but there had been a sizeable group of moderates willing to consider tax increases to prevent cuts in education and social services. That bloc, working with Democrats and Democratic Gov. Mark Parkinson, pushed through a sales tax increase in 2010 to help balance the state budget — with the help of Morris and other Senate GOP leaders.

Elections in 2010 shattered that coalition in the House, leaving the GOP with a 92-33 majority that was more conservative.

In 2011, the conservative-led House passed a bill to phase out individual income taxes, only to see it stall in the Senate without a vote. The House approved a 401(k)-style pension plan for new teachers and government workers, but senators’ wariness led instead to a study of the issue. The governor plans to outline a plan for cutting top individual income tax rates after lawmakers convene their annual session Jan. 9, and Morris has appointed a tax study group that could produce a rival proposal.

“I think part of the tradition of the Senate is to be more moderate and to try to govern the state,” said Senate Education Committee Chairwoman Jean Schodorf, a Wichita Republican who is among the moderates facing a challenger.

Active opposition

At least five challengers in GOP Senate primaries will be conservative House members. Schodorf’s opponent is House Health and Human Services Chairwoman Brenda Landwehr, of Wichita, who said she considers the Senate too liberal, arrogant and out of touch.

“That’s kind of the point I came to: All right, quit complaining and do something about it,” Landwehr said.

The state chapter of Americans for Prosperity plans to be active with independent campaigns about issues and incumbents’ and challenger’s records, Sontag said. The national group was founded with support from billionaire brothers and Wichita businessmen Charles and David Koch, who’ve also been Brownback supporters.

The Kansas Chamber of Commerce, the state’s largest business group, also is expected to help what its vice president, lobbyist Jeff Glendening, calls “free market” candidates.