Missouri Attorney General Chris Koster wants the state Supreme Court to set execution dates for two inmates before the state's supply of an execution drug expires.

Attorney General Chris Koster asked Missouri's highest court to set execution dates Monday for two long-serving inmates, arguing that time is running short to use a limited, nearly expired supply of a lethal injection drug.

Executions essentially have been on hold in Missouri since the state Supreme Court last August declined to set execution dates for six condemned prisoners. The court said then that execution dates would be "premature" until a federal legal challenge was resolved regarding the use of the drug propofol as Missouri's newly designated execution method.

Propofol gained public attention as the anesthetic drug that killed pop star Michael Jackson in 2009. It has never been used as an execution drug. Defense attorneys for Missouri inmates have asserted that it could cause extreme pain in violation the U.S. Constitution's protection against cruel and unusual punishment.

Drug maker Fresenius Kabi USA, a German company with U.S. offices based in Schaumburg, Ill., said last year that it won't sell propofol to states looking to use it in executions.

Meanwhile, Missouri's existing supply of the drug is aging.

The attorney general's office said in court documents filed Monday that the Missouri Department of Corrections has just three quantities of propofol remaining — with one expiring this October, another in May 2014 and the third in 2015. As each batch expires, the department's ability to carry out executions diminishes, the attorney general's office said.

"This Court should not allow the mere pendency of ongoing federal litigation to effectively eliminate capital punishment in Missouri simply because the lawsuits outlast the Department's supply of propofol," the attorney general's office wrote in a court document signed by Assistant Attorney General Stephen Hawke.

Koster's office specifically asked the state Supreme Court to set execution dates for two Allen Nicklasson and Joseph Franklin.

Nicklasson was convicted of the 1994 killing of Excelsior Springs businessman Richard Drummond, who stopped to help when a car used by Nicklasson and two others broke down on Interstate 70 in Callaway County. Drummond was forced to drive the group west, and then was shot twice in the back of the head in a field in rural Lafayette County.

Franklin was convicted of the 1977 sniper shooting of Gerald Gordon as a crowd dispersed from a bar mitzvah at the Brith Sholom Kneseth Israel Congregation in the St. Louis suburb of Richmond Heights. Two other men were wounded.

A drifter from Mobile, Ala., Franklin has said he tried to start a race war by traveling around the country shooting people. When he confessed in 1994 to the synagogue slaying, Franklin already was serving several life sentences in a federal prison for the murders of two black joggers in Salt Lake City and an interracial couple in Madison, Wis., and the bombing of a Jewish synagogue in Chattanooga, Tenn.

Franklin, who is white, was later convicted of killing two black teenagers in Cincinnati, Ohio, and a black man in Chattanooga, Tenn.

Attorneys for Franklin and Nicklasson did not immediately return messages left Monday.

Koster had initially asked in June 2009 that the state set an execution date for Franklin and had asked in January 2010 that a lethal injection date be set for Nicklasson.