Houston superdelegate defects from Clinton

And so they roll.

Democratic superdelegate and state Rep. Senfronia Thompson, of Houston, defected from Sen. Hillary Rodham Clinton's presidential campaign on Wednesday and joined a growing list of superdelegates to endorse Sen. Barack Obama for president, his campaign said.

"I'm honored to have earned the support of Representative Thompson and am pleased that she'll play an important role in advancing our grassroots movement for change in Houston and across Texas," Obama said in a statement. "Throughout her three decades in the Legislature, she's been a tireless advocate for working families and when I'm president we'll work together to put the American dream within reach of every child in Texas and across our country."

Thompson, one of the longest-serving Democrats in the state House, is one of the party insiders who, as a superdelegate, help choose the Democratic nominee at the national convention this summer in Denver.