Marco Rubio when he first signed up to run for the Senate in 2010. (Liz Sladky/AP)

Quinnipiac University's two most recent national polls have come at interesting points in the Republican contest. The first was in late December, after the collapse of Ben Carson and at about the midpoint of Ted Cruz's surge. The second was conducted this week, after the caucuses in Iowa. The change between those two polls looks like this.

A slight uptick for Donald Trump, a dip for Cruz — and a surge for Marco Rubio.

That Rubio surge is almost certainly thanks to his performance in Iowa, while the Trump increase is probably a function of timing. Quinnipiac's polls have shown lower support for Trump than have other surveys, but Trump's gain is probably a function of the December poll having preceded Trump's surge in January.

Overlaying those polls on the Real Clear Politics polling average, you can see the recent shift for Trump and Rubio more clearly. One down, the other up.

Part of the longstanding (and constantly rebuffed) skepticism over Trump has been that voters will sour on him once they turn their attention to electability. In other words, it's fun to flirt with the dramatic outsider candidate, but once it's time to figure out what Republican can beat the Democrat in the general, voting shifts.

Quinnipiac put the top three Republicans in head-to-head matchups against the Democrats, and Rubio fares the best, beating Hillary Clinton easily and tying Bernie Sanders. Sanders beats both Trump and Cruz. Clinton beats Trump and ties with Cruz. (Reminder: The value in these head-to-head polls is not predicting the winner of the presidency, but in comparisons like this.)

In theory, then, this is good news for Rubio. If he is seen as most likely to win, then he may attract support as the primaries continue. And indeed, Rubio's campaign is starting to press this electability message in its advertising — using phrases like "win in November" and "a conservative who can win."

But while electability was a big part of why Mitt Romney won the GOP nomination in 2012, early 2016 polls suggested it wasn't on people's radars. A July Washington Post-ABC News poll showed just 3 percent of GOP-leaning voters cited electability as their top priority.

Gallup has a new survey indicating that most voters still care more about a candidate that agrees with them on issues. Sixty percent of Americans would rather a candidate agree with them than be able to win. Less than 4 in 10 say it's more important that a candidate have the best chance of winning the presidency.

Interestingly, though, that's less the case with conservative Republicans than with moderates. Conservatives are more likely to want to win the presidency than worry about candidates hewing to orthodoxy.

That's good news for Rubio, who's often seen as straddling the line between the party's middle and far-right.

Gallup notes something else that should reassure Republicans worried about the ascent of Messrs. Trump and Cruz: The percentage of people who would take ideology over viability is at the same levels we saw in 2012. In other words, people now are saying they want someone who agrees with them politically over someone who can win in November to the same extent that they did four years ago.

Later in 2012, of course, that shifted in the favor of Romney, a more moderate candidate who they thought could win.