He directed his barbs instead at the president, while his staff urged supporters in this generally Republican and generally well-heeled section of Philadelphia's suburbs to divert their contributions to a November-focused "Romney Victory" fund.
Santorum, meanwhile, was 108 miles west, greeting supporters at a bowling alley outside Harrisburg and scrambling in anticipation of what he called a "must-win" primary in his home state. He did so even as the ultimate party elder - former GOP presidential nominee John McCain - called on him to make a "graceful exit" from the race.
"We still have a long way to go," Santorum said at the campaign stop in Mechanicsburg.
With the scene set for Pennsylvania's three-week Republican primary fight, both candidates were generally sticking with what they do best.
For Romney, a former management consultant, that meant emphasizing his business bona fides before a crowd of Republicans at the Iron Shop, a family-owned spiral-staircase manufacturing company in Broomall - and attacking the president, whose name was greeted with boos.
For Santorum, it meant hopscotching the western and central parts of the state he once represented in the Senate, jumping from one blue-collar setting to another - including stops at a Pittsburgh-area diner and a few frames of bowling in Mechanicsburg.
Expect much of the same over the next three weeks.
But for either candidate to take a commanding lead in Pennsylvania before April 24, each needs a little of what the other one already has, Republican analysts say.
Just more than a month ago, a poll gave Santorum that kind of lead - nearly 30 percentage points over Romney. That has since dwindled to fewer than 10 points, according to recent surveys by pollsters at Quinnipiac University and Mercyhurst and Franklin & Marshall colleges.
All through his 11 primary and caucus victories to date, Santorum has done best with rural and blue-collar voters, and evangelical Christians - who make up the majority of Republicans in northern and central Pennsylvania. And if his visit to Mechanicsburg on Wednesday night was any indication, he's likely to clean up in those regions.
Meanwhile, Romney's entourage, too, was wending its way across friendly territory - Philadelphia's vote-rich suburbs, where his appeal to more fiscally minded, moderate Republicans has sat well with most local GOP leaders.
Contact Jeremy Roebuck at 267-564-5218 or email@example.com, or follow on Twitter @jeremyrroebuck.