Mitt Romney insisted Sunday night on "60 Minutes" that his new running mate, Paul Ryan, is qualified to serve as president if the need arose. But in a warning sign for the campaign, incumbent Vice President Joe Biden is seen as a far better choice than Ryan to serve as president if needed, according to a new Reuters/Ipsos poll.

The poll found that by a whopping 44 to 29 percent margin, Biden was "more qualified" to serve as president if necessary, though a large number of voters remained uncommitted.

A USA Today/Gallup poll Monday found that 48 percent think Ryan is fit to be president. That's 9 points higher than Sarah Palin's initial 2008 numbers, but trails every other vice presidential candidate since 1988.

The Gallup/USA Today poll also found that Ryan received the worst initial reception as any vice presidential nominee since 1988, when Dan Quayle was the Republican nominee.

Historical data shows that although it's only one poll, the Romney campaign should be at least slightly concerned about the lack of a boost from its VP candidate. Shortly after John Kerry made John Edwards his running mate in 2004, Kerry received a surge in support, and Edwards led former Vice President Dick Cheney 45-38 in the presidential fitness question.

And in 1996 — when Ryan's mentor, Jack Kemp, was the vice presidential challenger to incumbent Al Gore — Kemp enjoyed a brief boost, trailing Gore by only 3 points in presidential fitness, before plunging in the polls after the vice presidential debate.