Mitt Romney caught a break on Friday and immediately turned it into a TV ad airing on the final weekend of the campaign:

It was an unseemly utterance by President Obama, which Romney wisely contrasted with an optimistic, patriotic appeal. Alone the president’s bitter remark and Romney’s retort would not have made such an impression, but this exchange of dueling messages has been going on for some time now.

Obama, having lost (or tossed aside) an appeal to independent voters, has been trying to whip up his base with a string of hot-button references and insults (e.g., Big Bird, “binders full of women,” “Romnesia”). The more he resorts to such gambits, the more Romney delights in appearing presidential, positive and inclusive. He made this pitch again in his Saturday podcast, exhorting voters: “Look, I know we face big challenges, and we don’t need more catchphrases or word games. We don’t need more of the same petty partisan attacks. We need a leader, a leader with a real plan that will deliver real results. My opponents have spent much of this campaign talking about small things. But the challenges we face are real and they are big.”

Whether you agree with Romney’s agenda, it is hard to quibble with that. The president has offered precious little on the great issues of our time (fiscal sanity, human rights, national security, entitlement reform). Yet his supporters insist that he’ll get to those topics in the next term. But if he didn’t accomplish any of this in the first, has made no effort to lay the groundwork for an agenda and instead has deepened the partisan divide, how is he to accomplish this? It is only by convincing themselves that Romney is a fool or mean-spirited that they can insist the do-nothing, say-nothing president is preferable.

It is far from clear that there are many persuadable voters, although every election the exit polls tell us a sizable chunk of voters made their choice on Election Day. (In 2008 that number was 4 percent, with another 3 percent in the final three days.) So there are still some votes to be had.

However, if the latest exchange (“Revenge vs. Love” sounds more like a Harlequin romance than an election standoff) has any impact, it may well be on all-important turnout. Republicans, many of whom distrusted and disliked Romney when the primary began, have come to respect and embrace their nominee, in part because there are glimpses now and then of their idealized memories of Ronald Reagan. The appeal to the better angels of our nature, the more-in-sorrow-than-in-anger countenance and the fiery defense of free-market capitalism resonate with these voters as those qualities struck a chord with voters in 1980. Conservatives are often portrayed as dour and negative (“the party of ‘No’ ”); when presented with a candidate who is running against a dour, negative and petty opponent, they can rejoice. Romney hopes that translates into a robust turnout on Tuesday. At least he can say that they have someone to turn out for.