Here is an interesting article about Sam Brownback's hypocrisy in attacking Romney from Matt Lewis at Townhall:

Clearly, Kansas Senator Sam Brownback (who recently spoke at the March for Life) is seeking to position himself as the only true social conservative in the presidential race. As such, he stands to gain if voters conclude that Romney’s past pro-Choice stance disqualifies him from their support.

But, it seems to me that voters are willing to forgive past mistakes. In fact, I would argue there is really only one unforgivable sin in politics – and that sin is the sin of hypocrisy …
Now, based on Brownback’s comments about Romney, you would assume that he has always been 100 percent solid on the Life issue, right? Well, it depends on whom you ask.

According to the Lawrence Journal World:
“Kansas Republican Party Chairman Tim Shallenburger said he remembered having a conversation with Brownback in 1994 when Brownback was running in the GOP primary for the U.S. House. After the conversation, Shallenburger said he left with the impression that Brownback “was not pro-life.”

And Shallengburger wasn’t the only Kansas leader who had the same recollection:
“David Gittrich, development director for the state’s largest anti-abortion organization, Kansans for Life, said when Brownback first ran for Congress in 1994 'he was ill-informed.' Gittrich added, 'He didn’t know whether he was pro-life or pro-choice.' … Gittrich said he had heard from others that Brownback simply didn’t understand the issues at the time."

A recent article in The New Republic (granted, this isn't exactly a conservative publication) notes that:
“As recently as 1994, the year of his first campaign for Congress, Brownback was a member in good standing of the moderate Republican establishment.”

The article also implies that Brownback co-opted his conservative opponents’ pro-Life stance, in order to win his the Congressional primary in ’94:
“… as primary day approached, (Brownback’s opponent) noticed a change in his opponent's language. Brownback never used to mention abortion on the campaign trail. Now he was publicly pronouncing himself an abortion opponent.”

Now, if Brownback did convert to the Pro-Life cause in 1994, I think we should celebrate it. Clearly, he has served in Congress as a champion for the Pro-Life cause. And whether his conversion came on the road to Damascus – or the “yellow brick road” to the White House -- is of little matter, so long as his conversion was sincere. But if Brownback is, in fact, a convert to the cause, it is concerning that he would question the sincerity of Romney’s conversion.
In fairness, Brownback disputes all of this. And maybe he’s right.

So I’ll end this simply by quoting Sen. Brownback's own words (this also comes from the CBN piece):
"I do think that when you get out on the campaign trail and the campaign really gets fully engaged, there's going to be a lot of discussion about where people actually stand on the issues.”
Indeed.