Last week I wondered how Mitt Romney would navigate the tricky shoals of the Iowa caucuses. This week, we have our answer; he is going all out to win. This ranks as one of the most important strategic decision of the campaign to date.

Fresh from a prod to his campaign from Iowa’s Republican governor, Terry Branstad, Romney has opened a large headquarters in Des Moines and plans to blanket the state with ads.

Romney has been playing a stealth Iowa game all along. The state ruined his 2008 campaign, and the conventional wisdom is that the state’s evangelicals -- the caucus’ prime voting bloc -- are not receptive to a Massachusetts Mormon with squishy conservative convictions.

But while many observers have been distracted by the gyrations of Cain, Perry and Gingrich, the Romney camp has been methodically focused on an Iowa “whites of their eyes” strategy. He wanted to keep his intentions as vague as possible for as long as possible to keep his options open.

Two factors have led Romney to this critical decision: necessity and opportunity.

The necessity stems from how the calendar sets up for Romney. If he allows another candidate to gain momentum in Iowa, he could have to wait until Florida to regain momentum. His win in New Hampshire will be discounted, and if he thinks Iowan evangelicals are inhospitable, wait until he meets those in South Carolina. Romney is close to becoming “the inevitable” nominee, and that can be a very precarious position -- where the choice becomes success builds upon success, or failure feeds failure.

Now for the opportunity. Romney knows that no other major candidate -- Gingrich, Perry or Cain -- has a significant ground operation in Iowa or the financial resources, as of now, to compete with his. Ron Paul, Michele Bachman and Rick Santorum, probably in that order, have some claim on the Republican caucuses’ base. It is worth remembering that caucuses are variable universes; more than any other state, a good ground operation in Iowa can expand the universe of normal attendees to favor the organizer.

Les jeux sont faits in Iowa (Ed, since you are not a Frankofile, that means the plays are made).