Rick Santorum’s presidential campaign released a new television ad overnight, which has caused a bit of a stir in Republican circles. Here’s the 30-second spot, which will begin airing in South Carolina as early as today:

For those who can’t watch clips online, the ad, called “Easy Answer,” features the following script:

“Obama supported the Wall Street bailouts. So did Romney.

“Obama gave us radical Obamacare that was based on Romneycare.

“Obama’s a liberal on social issues. Romney once bragged he’s even more liberal than Ted Kennedy on social issues.

“Why would we ever vote for someone who is just like Obama? When we can unite around Rick Santorum — and beat Obama.”

It’s obviously a pretty straightforward spot, hitting the Republican frontrunner on some of his intra-party weaknesses. Indeed, these are the kind of points many of us expected to be important in the race of the GOP nomination all along.

And therein lies the point: where has this ad been? It’s the kind of campaign commercial I would have expected to see in heavy rotation in, say, September and October.

Instead we’re seeing it in mid-January — after Romney locked up control of the race, and built up double-digit leads in South Carolina and Florida.

There’s nothing wrong with the ad; it’s relatively honest (by Republican campaign standards) and hits Romney on some key points. But like the religious right deciding to get organized after the process has largely been decided, I really don’t know why Romney’s rivals decided to wait until it was too late.

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.