For months, Mitt Romney’s presidential campaign has proven pretty adept at remaining focused. No matter what’s going on around him, the former governor stuck to his message, concentrated his attacks on President Obama, and was content to more or less ignore his Republican rivals. Romney started as the frontrunner, and so long as he acted like it, his nomination would look inevitable.

Call it the Gold Five strategy — during the attack on the Death Star in Episode IV, Gold Five was the Y-Wing pilot who, despite all kinds of threats around him and Darth Vader on his tail, kept saying, “Stay on target.”

Of course, things didn’t turn out especially well for Gold Five. By staying on target, he failed to appreciate the larger circumstances. Staying focused meant failing to adapt.

Romney’s Gold Five strategy made sense when Michele Bachmann was generating excitement and Jon Huntsman became a media darling, but Rick Perry has changed the game. Josh Marshall noted yesterday:

Okay, I don’t think Mitt is going anywhere soon. But two new polls show Perry opening up a big lead over the Mittster nationwide. That dramatically changes the contours of the race and — most significantly — ends Romney’s inevitability, de facto nominee strategy.

It’s quite true that we don’t nominate presidents in nationwide primaries. The problem for Romney is that the actual states that are going to be deciding are considerably more conservative than the GOP electorate nationwide.

Nate Silver added an analysis last night, detailing Perry’s surge, and noting that if Perry excels in Iowa, knocking out key conservative rivals, the Texas governor could pick up their collective supporters and be even stronger in New Hampshire and beyond.

Romney, then, can no longer simply stay on target, and pretend his Republican rivals don’t exist. The nomination will not be handed to him on a platter; he’s going to have to engage.

He’ll also, in all likelihood, have to move even further to the right. We saw the first hint of this yesterday when Romney, who said in June human activity has contributed to climate change, said the opposite.

Romney wasn’t an especially impressive candidate when he thought he was cruising to the GOP nomination. What kind of candidate will he be now that his lead has evaporated?

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.