...polls that were dedicated to Mr. Ryan specifically...offered mediocre numbers for the Republican ticket.

An ABC News/Washington Post poll, conducted after Mr. Romney’s announcement, found that 38 percent of Americans had a favorable view of Mr. Ryan, and 33 percent had an unfavorable one.

The good news for Mr. Romney and Mr. Ryan is that those numbers were improved from polling that ABC News conducted just before the announcement, when 23 percent of adults had a favorable impression of Mr. Ryan and 33 percent an unfavorable one.

But that is countered by two pieces of bad news. First, Mr. Ryan’s numbers are middling to poor by the standard of other recent vice-presidential selections. And second, the period immediately after a vice-presidential announcement has often been a high-water mark for the new candidate. More often than not, the candidate’s unfavorable numbers increase more than his or her favorables from that point forward...

A USA Today/Gallup survey posed a slightly different question to voters, asking them what they thought of Mr. Romney’s choice of Mr. Ryan, rather than about Mr. Ryan directly. In that poll, 39 percent of voters rated the choice as “excellent” or “pretty good,” while 42 percent called it “fair” or “poor.”

These are underwhelming numbers by the standards of this particular question, which Gallup has asked periodically since 1988. The scores for Mr. Romney and Mr. Ryan are a bit worse than those for John McCain and Mrs. Palin in 2008, and just slightly better than those for George H.W. Bush and Mr. Quayle in 1988 — two of the more poorly regarded vice-presidential choices of recent years.