Rep. Paul Ryan (R-Wis.) has publicly stayed neutral in the Republican primary race. That changed today when Ryan weighed in with remarks that certainly will bring smiles to the faces of Mitt Romney staffers.

In addition to praise for his organization, Ryan gave his stamp of approval to Romney’s agenda, which has incorporated many of Ryan’s ideas, calling the plan “very credible.” Even more helpful to the Romney team was Ryan’s back-of-the-hand treatment of Rick Santorum’s zero-tax rate for manufacturing. “It’s not from my playbook. I think we should have lower rates for everybody — broader based, stop picking winners and losers, stop doing special treatments and preference.” Ouch.

We’ve seen in this election, with Sens. Marco Rubio (R-Fla. ) and Pat Toomey (R-Pa.), that at a time when Washington pols are not in favor, sometimes an endorsement is worth less than a timely comment. If the comment comes from a credible conservative, the candidate can rightly claim that his position has been bolstered by a base favorite. Meanwhile, the pol extending the helping hand need not get some of his constituents mad by formally endorsing a candidate they may not like.

In the case of Ryan the comments may well set off a new round of speculation about Ryan’s V.P.-pick-prospects. That may not have been Ryan’s intention, but when you underline a major theme of one candidate (Romney called Santorum an economic “lightweight” yesterday) people will talk. Ryan’s office did not respond to a request for comment.