This tweet by Sen. Pat Toomey (R-Pa.) this morning got an unusual amount of attention: “@RickSantorum for Specter: wrong but ancient history. More importantly: @MittRomney’s strong pro-growth tax reform plan, very much like mine.” Until now, Toomey has remained quiet about the Republican race. But in last night’s debate Santorum’s decision to back Toomey’s opponent in 2004, Sen. Arlen Specter (R-Pa.), became a point of contention.

Toomey seems to be taking the high road about the endorsement. He knows better than anyone that had he, rather than Specter, won in 2004, conservatives would have been much better off. Toomey, who ran as a strict fiscal conservative was able to win in 2010 (in a tight race) and is a decidedly different sort of senator than was Specter on domestic issues.

I asked Toomey about his remarks. He replied via his spokeswoman. He again declined to focus on the endorsement issue, but chose to concentrate on the substance of his and Romney’s tax plans: “When I was on the Super Committee, I introduced a framework that lowered income tax rates for all taxpayers, while offsetting the lost revenue by primarily limiting itemized deductions. Gov. Romney introduced a similar plan yesterday, proposing the same marginal tax rates as my plan, and similarly reducing the value of deductions and maintaining the current treatment of dividends. This plan will stimulate economic growth by rewarding hard work, investment and productivity and will simplify our behemoth of a tax code. I hope to include the substance of this reform in my budget proposal this year.”

That’s not an endorsement. But as Sen. Marco Rubio (R-Fla.) showed in the Florida primary, sometimes it is more helpful for a candidate to have someone weigh in on the merits of an issue than to give a blanket endorsement.

This may add some volume to murmurs about a potential vice-presidential slot for Toomey. On some levels it makes a lot of sense. He is disciplined (a plus with the Romney team), has shown the ability to reach independent and Democratic voters in a purple state and has experience in facing an opponent with a problematic record on Israel (Toomey defeated Rep. Joe Sestak) .

To my knowledge he is not personally close to Romney, but his conservative rating (97 percent) and his time in the private sector would seem to be a good fit for Romney (who will need to bulk up on conservative bona fides). And yes, if one job of the V.P. is to be an attack dog, Toomey’s toughness would be an asset as well.