So far, Mitt Romney has not engaged with Rick Perry on the campaign trail, but that may be about to change.

The Washington Post's Mark Thiessen writes that Romney's campaign says they will go on the attack "at a time of our choosing." Perry's book Fed Up!, in which he argues that Social Security is unconstitutional, will be a centerpiece in that attack.

Look at what happened to Paul Ryan when he proposed a plan to save Medicare, they say. Romney’s campaign will argue that Perry is against the very idea of Social Security and Medicare, and that he will use Perry’s book to scare seniors in early-primary states with large retiree populations, such as Florida and South Carolina.

The Romney campaign also plans to use immigration to drive a wedge between Perry and his conservative base, by highlighting Perry’s opposition to a border fence and legislation he signed in 2001 allowing the children of illegal immigrants to attend Texas colleges and universities at in-state tuition. Without mentioning Perry by name, Romney pointed out at a town hall here in Dover that he vetoed similar legislation as governor of Massachusetts, declaring, “If you say, guess what, if you come here illegally, your kids will get [in-state tuition], that draws more people here illegally.” Romney strategists believe the immigration issue will be devastating for Perry with Tea Party Republicans across the country — and especially in important primary states like Arizona.

Team Romney intends to undermine Perry’s appeal on the right by painting him as the anti-government candidate who has spent most of his life in government — first as a state legislator, then as agriculture secretary, lieutenant governor and governor. They will tar Perry as an old-style Texas, pay-to-play, career politician whose state is worse off now than when he first took office. They will contrast Perry’s quarter-century in government with Romney’s 25 years creating jobs in the private sector. Romney hinted at this line of attack at a town hall meeting in Keene last week, declaring, “I won’t just have been somebody who watched jobs be created, I actually created jobs.. . . I spent four years in government. I joke that I didn’t inhale.”