One of the more perplexing mysteries of the universe is why lawmakers, who in general are careful cultivators of their image, freely accept an invitation to be made fun of on “The Colbert Report.”

Now an answer comes from Republican Rep. Lee Terry, of Nebraska’s Fighting 2nd district. Terry acknowledged host Stephen Colbert had made a fool of him in a column on the subject that appeared in the Los Angeles Times on Monday. But Terry added that the interview was “one of the best” the rank and filer had made since he started serving in Congress.

Not only did Americans outside of Omaha get to know something about the district, Terry said the show also gave him to opportunity to let his constituents know that he can take a joke. He said he has never had as much feedback from a TV appearance as he’s had subsequent to appearing on Colbert. He also said that the rest of the country now knows that the First National Center is the tallest building between Minneapolis and Denver.

Terry also chided House Minority Leader Nancy Pelosi (D-Calif.) for warning members away from the show, and urged lawmakers “to put aside their political differences and let Stephen Colbert make fun of both parties equally.”

There’s been plenty of mud-slinging in their campaign, but last week Minnesota Senate candidates Rep. Mark Kennedy (R) and Amy Klobuchar (D) moved to something a little harsher – manure.

Don’t worry, they weren’t actually throwing it. In fact, they agree it’s not hazardous – and neither was their humorous exchange over the issue at FarmFest in Redwood Falls, Minn.

According to the Grand Forks Herald, Kennedy accused Klobuchar of believing manure is toxic waste because one of the organizations supporting her says it is.

Klobuchar said she doesn’t necessarily agree with her endorsers and challenged Kennedy: “If he wants to go down in the manure, I will go down with him.”

Kennedy said Klobuchar is afraid to take a position on the issue. “You know where I stand,” he said, reportedly emphasizing the remarks by pointing his finger into a reporter’s face.

Rest assured, it won’t be the last time a candidate talks crap.

Two Pennsylvania lawmakers late last month praised cyclist – and constituent — Floyd Landis for his dominating win at this year’s Tour de France.

Sen. Rick Santorum (R-Pa.) said Landis “has become the face of American cycling, and, frankly, we could not ask for a better spokesman.”

Rep. Joe Pitts (R-Pa.) called Landis’s performance an inspiration, adding that “he represented his hometown and his country well.”

Of course, these statements were made before the controversy about Landis’s high testosterone levels and accusations that he took substances that helped him win the Tour de France.

Despite two tests that indicate Landis’s testosterone levels were unnatural, Landis has denied any and all wrongdoing.

So do Santorum and Pitts believe Landis?

Santorum spokesman Robert Traynham said, “The senator is deeply troubled [by the allegations] and like all Americans, was surprised by the news.” Traynham noted that “we live in a society where you are innocent before proven guilty” and that Santorum is “very hopeful” that Landis will be cleared.

Pitts spokesman Skip Brown said the House lawmaker is also hopeful, but added if Landis is guilty, Pitts and his constituents will be “devastated.”

Senate Republicans lost their bet last week on the level of Democratic support for a package of popular tax extenders, a minimum-wage hike and a steep estate-tax cut — a legislative gambit that one House Republican boasted had “outfoxed” the opposition.

But even before the “trifecta” bill failed on long odds to overcome a filibuster, Senate Finance Chairman Committee Chuck Grassley (R-Iowa) couldn’t resist a rejoinder to House Ways and Means Committee Chairman Bill Thomas (R-Calif.), Grassley’s longtime conference committee nemesis and one of the trifecta concept’s chief architects.

In a colorful floor statement during debate on the trifecta measure, Grassley began by noting that a $2 trifecta bet on this year’s Kentucky Derby would have paid $11,418. The legislative long shot, Grassley continued, “was the result of my ‘wily’ counterpart. You know the guy who, according to House colleagues and staff, supposedly ‘snookers’ the Senate year in and year out in conferences.”

The Ways and Means Committee declined to comment on whether Thomas would have preferred “clever,” “crafty” or “cunning.”

If you are a member of the Senate, there’s better than a one-in-five chance that you’ve also written a book. With the recent publication of his book on the outsourcing of American jobs to low-wage countries, Sen. Byron Dorgan (D-N.D.) becomes the 22nd sitting senator who’s written a book while in office, according to the Senate Historical Office and Senate Library.

Dorgan’s “Take This Job and Ship It: How Corporate Greed and Brain-Dead Politics are selling out America,” published in July by Thomas Dunne Books, is No. 373 on the Amazon.com sales list, and has received generally favorable reviews, including one by a reader who described himself as a “staunch conservative Republican” who thinks Dorgan “is right on the money.”

Dorgan joins Sens. Gordon Smith (R-Ore.) and Edward Kennedy (D-Mass.) as the only senators who have published books this year, although Sen. Barack Obama’s (D-Ill.) second book, “The Audacity of Hope: Thoughts on Reclaiming the American Dream,” is scheduled for publication in October.

Obama’s first book, “Dreams from My Father: A Story of Race and Inheritance,” earned him $378,000 in royalties last year, and he received an $847,167 advance for his second book.

But Sen. Hillary Rodham Clinton (D-N.Y.) has made the most money by far as an author. She received an $8 million advance for her 2003 autobiography, “Living History,” which earned her $872,891 in royalties last year.

Kennedy and Sens. Robert Byrd (D-W.Va.) and John McCain (R-Ariz.) are the most prolific authors or co-authors, each with five books to their credit, while Sens. Bill Frist (R-Tenn.) and John Kerry (D-Mass.) each have four; Sens. Orrin Hatch (R-Utah) and Richard Lugar (R-Ind.) three each; and Sens. Pete Domenici (R-N.M.), Jim Jeffords (I-Vt.), Joe Lieberman (D-Conn.) and Barbara Mikulski (D-Md.) two each.

But none is likely to match the record of the most prolific senator-author, the late Henry Cabot Lodge (R-Mass.), who has 10 books to his credit.

Aaron Blake, Albert Eisele, Elana Schor, and Jim Snyder contributed to this page.