Ryan, 42, but looking younger, is little known outside of Washington. What he is known for -- turning Medicare into a voucher system and adding individual accounts to Social Security -- is not particularly popular with older voters, a vital electoral demographic.
Even though their party is solidly in control of the U.S. House, Republicans hope to capitalize on anti-Washington sentiment this fall. But by no stretch of the imagination can Ryan be considered an outsider. He came to the Capitol fresh out of college and has been there ever since, first as a staffer, then as a member of Congress.
House members, because of their comparative obscurity, are not usually anyone's first choice for the second spot on the ticket. The last House member to fill Ryan's role was Geraldine Ferraro, a New York Democrat, and she and Walter Mondale went down to a crushing defeat. You have to go back to 1932 to find a House member who successfully made the transition: Franklin D. Roosevelt's vice president, John Nance Garner.
Romney could have gone with the two safer choices among his finalists: Ohio Sen. Rob Portman, who could help deliver that key swing state, and former Minnesota Gov. Tim Pawlenty, an indefatigable campaigner and a veteran of two unsuccessful runs for the presidency.
Ryan's appeal to women voters, independents and wavering Democrats is likely to be weak, but that's not the role Romney apparently has in mind for him. The choice of Ryan was to reassure and fire up the Republican right, which has been openly skeptical of the former Massachusetts governor who enacted the prototype for Obamacare.
The right was ecstatic at the choice, and Ryan got a full-throated endorsement from the tea party types. He brings something else to the table: He could turn out to be a prodigious fundraiser. His selection brought in $3.5 million the day it was announced, and the Romney campaign quickly organized 10 high-dollar fund-raisers for Ryan during the next two weeks.
As he contemplated running for president in his last year in the Massachusetts statehouse, Romney began reversing or discarding long-held positions -- pro-choice being one of them -- in preparation for seeking the nomination in an increasingly conservative GOP.
His choice of Paul Ryan completes that migration to the right.
Dale McFeatters is a senior writer for the Scripps Howard News Service.