WASHINGTON -- Sen. Kay Bailey Hutchison of Texas has endorsed presidential Republican candidate John McCain.

Hutchison was to officially announce her endorsement Monday afternoon. Her office said she also plans to campaign with McCain in Texas before the state's March 4 primary.

Hutchison has been considered a possible vice presidential candidate. She has said she's not seeking the job but wouldn't turn it down if the party's nominee asked her to join the ticket.

Hutchison is the only woman in Senate Republican leadership. Her presence on the ticket could help Republicans offset Hillary Rodham Clinton if she is the Democrat's presidential nominee.

McCain, an Arizona senator, is all but assured of winning his party's primary.