By Bruce Olson

ST. LOUIS (Reuters) - A plan to place a bust in the Missouri Capitol of Rush Limbaugh, the conservative broadcaster embroiled in controversy over his calling a university student a "slut" on the air, has upset local Democrats who are trying to block the effort.

The bust of Limbaugh, proposed by Republican state House Speaker Steve Tilley, would sit alongside prominent Missouri natives such as writer Mark Twain and former president Harry Truman in the Capitol rotunda.

Missouri Democratic U.S. Senator Claire McCaskill, who was once called "a commie babe liberal" by Limbaugh, said she opposed honoring him.

"I draw the line," at putting Limbaugh's bust in the Capitol, McCaskill told MSNBC on Monday.

About 1,300 people have signed an online petition protesting the plan to honor the conservative Limbaugh in the Hall of Famous Missouri natives, the head of a liberal group said Tuesday.

Sean Soendker Nicholson, executive director of Progress Missouri, said that the Hall should be reserved for people who favorably represent Missouri or its government.

"Rush Limbaugh has made his living as a divisive and spiteful individual," Soendker Nicholson said. Limbaugh has been in the news over the last week for calling a birth-control activist who testified to Congress a "slut" and a "prostitute."

Some advertisers have dropped his radio talk show and some radio stations have said they will no longer air it.

Missouri Democrats in the legislature are also gathering signatures from lawmakers to oppose the installation.

The hall, located in the state Capitol rotunda in Jefferson City, Missouri, includes a ring of busts also including baseball great Stan Musial, ragtime composer Scott Joplin and writer Laura Ingalls Wilder.

Speaker Tilley made the decision to honor Limbaugh about three months ago. The bust will not be unveiled until May.

Limbaugh apologized on Monday for the "slut" remark, saying he had gone too far in his attack on the birth-control activist, Sandra Fluke.

It was not clear if the Democratic opposition could stop the installation of the bust. The House Speaker has traditionally made the decision and money for the bust was raised privately.

Republicans majorities control both the Missouri House and Senate.

Tilley, like Limbaugh, hails from southeast Missouri, and defended his decision in a statement on Tuesday.

"Due to the nature of the career paths many inductees chose, current members of the hall often had detractors and were not always uncontroversial or universally loved and adored," Tilley said. "Rush's work in broadcasting revitalized the talk radio format and many say he even saved the AM dial from extinction," Tilley said.

He added that Dred Scott, a slave whose St. Louis court case led to the controversial U.S. Supreme Court decision that helped to ignite the Civil War, would also be honored this year.

Twain, the 19th century author and acerbic political commentator whose remarks were also controversial, was the first inductee, taking his place in the rotunda in 1982. The hall also includes astronomer Edwin Hubble and game show host Bob Barker.

Money for the busts, which cost about $10,000, is raised at an annual golf tournament sponsored by the speaker, who chooses the inductees.

(Reporting and writing by Bruce Olson; Additional reporting by Kevin Murphy; Editing by Mary Wisniewski)