Michael Steele uses former Gov. Christie Todd Whitman as proof Republicans are a 'Big Tent' party. She quit the GOP in 2003

Crooks and Liars:

David Gregory asked Michael Steele for an example of the GOP being as inclusive a party as the Democrats since Kaine is pro-life. Steele uses Christie Todd Whitman as his example to show America how "Big Tent" they really are.
Gregory: Is the Republican Party open to pro-abortion right candidates in the way that Gov. Kaine has survived in the Democratic Party?

Steele: We've had wonderful pro-choice candidates. Gov. Christie Todd Whitman for example was a very successful republican Governor...
She was so happy with the GOP that she quit the Republicans in 2003 after she was picked to lead the EPA in 2001 by Bush and then refused to do their bidding.

Wikipedia: Whitman was appointed by President George W. Bush as Administrator of the United States Environmental Protection Agency, taking office on January 31, 2001.

She refused to go along with Bush and Cheney over their pollution quest and resigned from the EPA:

On June 27, 2003, after having several public conflicts with the Bush administration, Whitman resigned from her position to spend more time with her family.[31][32]