How much shifting must they do?

The Texas governor dropped in on the wacky world of Massachusetts Republicans the other night. He listened to a long, wonky speech about pension reform, joining an audience that included former Massachusetts Governor William F. Weld, who endorsed Barack Obama over fellow Republican John McCain.

When it was finally his turn to speak, Perry didn’t pull a Mitt Romney. He didn’t tailor his message to fit the crowd.

In a speech to the conservative Pioneer Institute, delivered in Boston on Romney turf, Perry stuck to his Social Security guns. Every Republican candidate, he said, “knows that the current system is unsustainable, with an unfunded liability in the trillions of dollars.’’ Without naming Romney, he told the crowd “Other candidates. . . have used words like ‘fraud’ and compared it to a ‘criminal enterprise.’ But under the media spotlight, they change their tune and they start sounding like liberals.’’

He’s right. On the debate stage, Romney is sounding more like Al Gore, who back in 2000, famously pledged to keep Social Security in a lockbox. Unsurprisingly, what Romney’s saying now isn’t exactly what he said before.

In his book “No Apology: The Case for American Greatness,’’ Romney peeks into the lockbox and informs readers that even FDR “would be surprised to see how much it has grown.’’ Americans “have been effectively defrauded out of their Social Security,’’ Romney writes. He also refers to the program’s “looming bankruptcy,’’ an outcome he blames on Congress. There’s “certain logic,’’ Romney writes, to gradually increasing the retirement age. He also entertains the possibility of calculating benefits based on income and discusses privatizing options.

Recalculating is so Romney that one more example barely triggers headlines. But a series of recalculations might. That’s the threat Perry poses to Romney. How much more shifting will Romney do, now that Perry’s in the race?

After 2008, Romney plotted his new strategy for 2012. He would focus on the economy and his business résumé. He would leave the Tea Party and the religious right to Sarah Palin or, now, to Michele Bachmann. Then, along came Perry, bringing to the Romney endeavor exactly what business executives hate - uncertainty.

Perry’s path is uncertain too. He held his own in the last two debates, but Bachmann hurt him in their most recent showdown. Her attack on his push to require Texas pre-teen girls to be vaccinated against a sexually transmitted virus gained altitude once she pointed out the financial support he’s received from Merck & Co., which manufactures the vaccine.

According to a Bloomberg News report, Perry received at least $23,500 in campaign contributions from the drug company, including $5,000 in 2006, the year before he ordered girls to take the vaccine. The drug-maker also donated about $500,000 to the Republican Governors Association, a group that Perry headed twice and has been among his most generous campaign donors, Bloomberg reported. His former chief of staff also worked for a lobbying group retained by Merck.

Perry previously said he “hated cancer’’ and that’s why he issued an executive order that girls be vaccinated against a virus that can cause cervical cancer. On the basis of that explanation, Romney even defended him, saying Perry’s “heart was in the right place.’’ Romney’s graciousness is even more understandable, given that Perry’s executive order regarding the vaccine makes it harder for Perry to attack RomneyCare. But if Perry’s heart was in his campaign chest, instead of “the right place,’’ that’s another matter.

So far, Romney is relying on mutual rivals to beat up on the Texas governor. But Perry’s address to the Pioneer Institute irked Romney’s inner circle, and that was even before Perry took the podium. There was considerable unhappiness over the Romney-aimed barbs.

But what does Romney do about a rival like Perry who tells Romney and others what they don’t want to hear? How does he handle an opponent who comes across as a socially conservative Bill Clinton? Perry feels your pain, even as he’s ordering executions and pledging to dismantle federal entitlement programs.

If you’re Romney, you must be thinking, someone better knock Perry off his high horse, and soon.

Joan Vennnochi can be reached at vennochi@globe.com.