The Senate opened on a somber tone this morning, as members paid tribute to Sen. Craig Thomas, R-Wyo., who died last evening of acute myeloid leukemia.

Thomas, 74, was first diagnosed last November, just as he was winning election to a third term with 70 percent of the vote. He returned to work last December but suffered a recurrence of the cancer this spring that proved resistant to further treatment.

Minority Leader Mitch McConnell, R-Ky., memorialized Thomas as “the modern day embodiment of the cowboy ideal he celebrated and loved.”

Thomas compiled a conservative voting record, supporting his party 97 percent of the time last year on votes that pitted the two parties against each other. He backed President Bush on 91 percent of the votes on which Bush staked out a position.

Under Wyoming law, Democratic Gov. Dave Freudenthal will appoint a successor from a list of three candidates to be submitted within two weeks by the Republican state central committee.The appointed senator will serve until a special election in 2008 to fill out Thomas’ term.

Among Republicans seen as possible contenders are Colin M. Simpson, majority floor leader of the Wyoming House and son of former Sen. Alan K. Simpson, R-Wyo. (1979-1997); former state House Speaker Fred Parady, who ran unsuccessfully for the Republican nomination for state treasurer in 2006; former state Treasurer Cynthia Lummis (1999-2007), who was term limited out of office in 2006; and Max Maxfield, who was elected secretary of state for Wyoming in 2006.