Story highlights Rick Santorum served 12 years in Senate, 4 years in House

Three House members have endorsed him, no sitting Senators have

Santorum aides say he hasn't done much lobbying of former colleagues

There is a Senate tradition dating back to 1965. One specific desk in the Senate chamber has a drawer filled with candy. The senator assigned to that desk is responsible for keeping candy in it and providing sweets to all his or her colleagues.

Rick Santorum had the desk with the candy drawer, yet all that sugar didn't win him any endorsements for his presidential bid from former Senate colleagues.

Santorum was in the Senate for 12 years. He served in the House for four years before that. Yet only three House members have endorsed him, and he has no endorsements from any sitting senators.

Mitt Romney, who never served in Congress, has racked up 77 congressional endorsements, including 12 senators.

Ask Santorum's former Senate colleagues about his bid for president and many refuse to comment.

"That's not the purpose of the news conference," responded Sen. Lindsey Graham, R-South Carolina, who served with Santorum in the Senate and the House.

At another news conference, Sen. John Thune, R-South Dakota, simply said he came out early for Romney.

"I think he's in the best position to win the election," Thune said of Romney.

Sen. Kay Bailey Hutchison, R-Texas, was one rank below Santorum in the GOP leadership. She declined to step forward to the microphone to talk about Santorum.

When asked by CNN if she could say anything good about him, Hutchison cautiously replied, "Certainly he's a very nice person, but I'm not going to do presidential politics right now."

So, why the lack of support for the former senator? Most observers point to questions about Santorum's electability. Multiple GOP Senate sources tell CNN many who were in the Senate trenches with Santorum like him personally, but don't think he can win the presidency.

They recall fiery speeches on the Senate floor about social issues from abortion to same-sex marriage.

"Society should be all about creating the best possible chance for children to have a mother and a father," Santorum said on the Senate floor in 2004.

"Unless our laws enforce that, then I think it's fairly obvious that our culture will not," he said.

One veteran GOP leadership aide called him a culture warrior likely to turn off moderate voters.

"The fear of Santorum is that it would just be a slow decay. There is no faith that he would bring independent or moderate voters. If he does well on Super Tuesday you'll have serious people talking about convention strategies," said the Senate GOP leadership aide.

When former House Speaker Newt Gingrich was on the rise, many of his former colleagues were openly nervous, calling into question his leadership ability.

The same GOP leadership aide said with Santorum, it's a "quieter freak out. It's a freak out, just it's muted."

Another GOP leadership aide agreed, saying people "would be pretty nervous" if Santorum does well in big contests March 6, Super Tuesday.

Republican Senate sources tell CNN that colleagues often privately point to Santorum's crushing 18-point loss in his 2006 re-election bid.

But Pennsylvania Rep. Glenn "GT" Thompson dismissed all that. He's one of the three House members to endorse Santorum.

"We learn from these experiences, and I think that probably that experience in 2006 prepared Rick to be a better public servant. You learn as many lessons from elections that you've lost -- in fact I think you learn more from that than what you do when you win," Thompson said.

Thompson noted that Abraham Lincoln was "soundly defeated" in elections before he was president.

As to the Republican concern that Santorum is too polarizing on social issues to win over moderates and independents, Thompson said that's overblown.

"He recognizes what the No. 1 task and hurdle facing this country (is) and it's jobs, and I like the fact that he talks about manufacturing, and small businesses in particular, as the backbone of this country economically," said Thompson, who also noted that there hasn't been a president from Pennsylvania since James Buchanan at the beginning of the Civil War.

Thompson said Santorum personally called him early on in his campaign for president and asked for his endorsement.

Drew Cantor, a former Santorum Senate aide, brushed aside talk that Santorum is too polarizing a figure on social issues to bring moderates and independents into the fold.

Cantor said when Santorum was chairman of the Republican Conference, the No. 3 position in the Senate GOP leadership, he "understood the role of conference chair was promoting relationships and unity in the conference. He played that role effectively."

Santorum campaign aides said he hasn't done much lobbying of former colleagues, and said that may be one reason he hasn't gotten any endorsements yet from his former stomping grounds in the Senate.

Sen. Thad Cochran, R-Mississippi, who endorsed Romney early on, said he never got a call from Santorum, despite the fact the two of them are personal friends, and often played tennis together.

When asked if he thinks Santorum would make a good president, Cochran chuckled nervously and said, "Oh, I don't know."

Cochran then said he just thinks Romney is "ideally suited for a very challenging job."

Other Republican senators who have not endorsed any GOP candidate are quick to say nice things about Santorum.

"He's knowledgeable, and conservative," said James Inhofe, R-Oklahoma.

Inhofe had endorsed Texas Gov. Rick Perry, who dropped out of the race last month.

His home state of Oklahoma has a contest coming up, and is a place Santorum aides said he is competing in aggressively.

Why won't Inhofe endorse Santorum?

"That's my judgment," Inhofe replied.

Other Senators simply want to stay out of the endorsing business.

Sen. Saxby Chambliss, R-Georgia, said he won't back any of the GOP candidates because they're all his friends.

Alabama Republican Sen. Jeff Sessions said, "I love Rick Santorum. I think he'd be a great president."

So, why won't he endorse Santorum?

"I haven't endorsed anybody," said Sessions.

While Santorum aides said they welcome support anywhere they can get it, they also downplay the importance of high profile endorsements.

After all, Mitt Romney's point person in the Senate is Roy Blunt, Republican from Missouri.

Last month, Romney lost that state to Santorum, and lost it big.