Hard for Clinton to give up when she's still winning

By Steve Holland

WASHINGTON (Reuters) - For Democrat Hillary Clinton, it is hard to think about giving up her presidential run when she is still winning state contests.

Given little hope of capturing the Democratic presidential nomination over rival Barack Obama, still Clinton fights on. She captured West Virginia on Tuesday and is expected to win Kentucky on May 20.

What is her motivation? Why keep campaigning if the game is over, since it is next to impossible for her to catch Obama's lead in nominating delegates?

Clinton herself gave the simplest explanation after winning Indiana and losing North Carolina last week, saying she was in the race until a nominee is selected, and that Obama has not locked it up.

Or as the pantsuit-wearing Clinton quoted from a Mother's Day letter to her in West Virginia: "It's not over until the lady in the pantsuit says it is."

Theories abound all over Washington as to why she is staying in a race that has lasted more than 17 months and left her about $20 million (10 million pounds) in debt, including $11 million out of the family bank account.

There is the "Clinton-the-fighter" theory: that she and her husband, former President Bill Clinton, have faced daunting odds throughout a long, colorful political career and are loathe to cede the battlefield.

"You can see that they are not quitters and they are people who gut it out," said Democratic strategist Jennifer Palmieri, who worked in the Clinton White House.