John McCain just gave a major speech on the economy. It was a good speech, emphasizing exactly the right problems — the lack of transparency and accountability in financial markets.

But what leaps out at me here is that as the economy worsens, the more Vice-President Willard Milton Romney makes sense. I just got off the phone with Jeremy Lott, who’s just written The Warm Bucket Brigade, a fantastically entertaining book about the vice-presidency, and as he noted, vice-presidents are traditionally chosen because they can be counted on to deliver a certain constituency or convey a particular message.

Well, it’s unlikely that Mitt will flip Massachusetts to red, but in addition to having great fundraising network, and being ten years younger and a tireless campaigner, he brings one heck of a message. Romney’s mastery of economic issues and rep as the business turnaround guy could prove highly valuable to McCain. (Not to mention the healing to party divisions it might prompt.)

While McCain hogs the campaign trail spotlight, Romney could quietly barnstorm the most depressed areas of the country laying out a plan to tackle economic woes. His expert knowledge here and relentlessly upbeat demeanor would probably go over well. Further, his expertise means he could go out on the attack against the other candidate(s) on the issue with confidence and ease as the McCain camp needs him to.

Once elected, Romney could continue to deal with the issue. Being weighed down with concerns over the domestic economy is probably not what McCain wants anyway. President McCain would then be able to focus in on the issues he cares about — the war, national security and congressional/fiscal corruption. Romney would have to be careful not to overshadow McCain, but if the economy improves he could take some measure of credit for it and end up with an elevated profile to set him up for his own run at the White House, which could prove crucial if McCain ends up going one term.

There’s bad blood still left over from the primary, but Romney appears willing to bury the hatchet. If McCain’s smart, he’ll look past that and start objectively weighing the merits of Veep Romney now.