Warming up the crowd at Mitt Romney’s morning rally here Sunday morning, Iowa congressional candidate John Archer strode on stage and took what in Republican circles has become a tried-and-true dig at President Obama.

“Wow,” he said, “I don’t need these teleprompters!”

What Archer may not have realized is that the twin teleprompters erected at both sides of the podium had been set up for his own party’s nominee. Like the president, Romney has been relying more and more on teleprompters in recent days as he swoops in and out of the battleground states delivering a scripted closing argument.

Romney’s heavy use of teleprompters symbolizes the evolution of his stump speech. Throughout this campaign, Romney usually spoke extemporaneously and with only a few written notes. For formal policy addresses, he read his prepared remarks from teleprompters. But for his standard rallies, he stitched together his speeches, seemingly off the cuff, from an assortment of well-practiced and familiar riffs. He regularly took jabs at Obama’s eloquence, often noting to loud applause that sterling rhetoric does not make a sterling record.

But with his closing argument speech — which he debuted Friday morning in West Allis, Wis., (using teleprompters) — Romney is reaching for sterling rhetoric of his own. The speech is loftier than those he has given before, as he talks in big, sweeping terms about his promise for American renewal. And he is relying on a written script to deliver the words just right; at five of his seven rallies since the Wisconsin speech, Romney has read from teleprompters.

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Romney’s aides said the candidate would keep using teleprompters on the home stretch because his closing argument speech is new and he wants to achieve precision and accuracy as he lays out his fresh message. “We don’t have a problem with teleprompters,” one aide said.

To be sure, Obama regularly uses teleprompters — a trusted accessory for all presidents and many presidential candidates, Republican and Democratic alike, since the device’s invention a half-century ago.

But in recent years, conservative commentators have made hay out of Obama’s use of teleprompters. During the Republican primary campaign, businessman Herman Cain and Rep. Michele Bachmann (Minn.) pledged to ban teleprompters if they made it to the White House.

“President Bachmann will not have teleprompters in the White House,” she thundered at an Iowa rally last year.

Even Romney got in on the fun. When he rolled out his 59-point economic plan in September 2011, he held up a single page of hand-written notes on a legal pad. “I don’t have a teleprompter here,” Romney said, as his aides whispered to reporters that he had sketched out the speech the day before on a Southwest Airlines flight.

But even his new teleprompters haven’t kept Romney from making small mistakes. The candidate, his voice sounding tired and a bit hoarse from long days of barnstorming, said “employment” instead of his intended “unemployment” at his Saturday morning rally in Des Moines.

“Employment is higher today than when Barack Obama took office,” Romney said.

The crowd didn’t pick up on the gaffe and Romney pressed on. It was as if he hadn’t even noticed.