Sen. Blanche Lincoln (D-Ark.) turned down an offer from NBC to debate Lt. Gov. Bill Halter (D-Ark.) on "Meet the Press."

Halter, who is challenging Lincoln in the Democratic primary, had been willing to participate in the proposed May 9 debate.

Lincoln campaign spokeswoman Katie Laning Niebaum said Monday that the two-term Democrat planned to spend Mother's Day with her mother.

"It's not surprising that Bill Halter would welcome another trip to Washington since most of his support is based there," Niebaum told the Arkansas News Bureau. "However, Sen. Lincoln will not interrupt her plans to be in Arkansas with her family on Mother's Day in order to appear before a national television audience, most of whom do not vote in Arkansas."

Halter said he is willing to be flexible in order to facilitate a MTP debate. 

"We have told Meet the Press that we are available to debate Senator Lincoln any time between now and May 18th -- whether that be on a Sunday morning, or pre-taped at the Senator's convenience," he said in a statement. "We have also invited Meet the Press to come here and film a debate in Arkansas and would be proud to have them showcase our beautiful state to the entire nation."

Halter called the show a "wonderful way" for Arkansas voters to get to know the candidates. "I thoroughly enjoyed our last debate and I am looking forward to our having more of them," he said.

Halter and Lincoln had their first televised debate on Saturday in Little Rock.

(This post was updated at 6:47 p.m.)