Romney will make his official announcement Saturday at 6 a.m. PT in Norfolk, Va.
Conservatives have waged a strong campaign, pressuring Romney to select the Wisconsin congressman. He has a reputation as a fiscal conservative.
Ohio Senator Rob Portman, thought to be on the short list, confirms that he will not be in Norfolk Saturday, and former Minnesota Governor Tim Pawlenty said he won't be there either.
Romney's announcement follows an onslaught of negative political ads by Democrats that are apparently having an effect. Three new polls show President Obama widening his lead over Romney.