The bizarre spectacle taking place in the Senate over a human trafficking bill continues to descend to new lows.

The ostensible reason the bill is being held up is that it contains pro-life language Senate Democrats dislike, even though the Hyde amendment banning most Medicaid funding of abortion has been around since 1976. Other issues also seem to be in play. (RELATED: Senate Democrats Fight For More Illegals In Anti-Prostitution Bill)

Now the debate is delaying a vote on whether to confirm Loretta Lynch as Eric Holder’s successor at the Justice Department, a fact that has occasioned much wailing and gnashing of teeth.

Ten of the trafficking bill’s 13 Democratic cosponsors voted to filibuster it Tuesday, including Senate Minority Whip Dick Durbin. But that isn’t Durbin’s biggest position change: the Illinois Democrat was once pro-life.

In 1982, Durbin bragged about being a five-time master of ceremonies at annual pro-life rallies in Springfield — while competing in a Democratic primary. He supported overturning Roe v. Wade as late as 1989, even voting for constitutional amendments to that effect.

By 1995, Durbin was opposed even to making partial-birth abortion illegal. National Review’s Ramesh Ponnuru observed in his book “The Party of Death” that Durbin insisted John Roberts must support Roe in order to be confirmed to the Supreme Court.

“What Durbin was saying,” Ponnuru wrote, “was that Roberts should be disqualified for the job for taking the exact same position that Durbin took in the 1980s.”

Joe Biden also voted for a pro-life, anti-Roe constitutional amendment that stated, “the right to an abortion is not secured by this Constitution.”

By the time Biden first ran for the Democratic presidential nomination in 1988, he was pro-choice. That field also included several other prominent abortion flip-floppers: Jesse Jackson, Dick Gephardt, Al Gore and Paul Simon.

And by Paul Simon, I mean the late Illinois senator, not the singer. Though like “The Boxer,” the pro-life Democrats’ story is seldom told.

The most interesting case is Senate Minority Leader Harry Reid, who once took the position that abortion should only be legal in cases of rape, incest and when the life of the mother is in danger. In 2003, Reid was one of only three Democrats in the Senate to vote against an amendment affirming that Roe was decided correctly.

What makes Reid remarkable is that he has never publicly changed his position, even if he now blocks bills that restrict federal funding of abortion. Pro-life Democrats celebrated as Reid rose up the party’s Senate leadership ranks. Democrats for Life listed him as an “all star” in 2004, after he had been the Democratic whip for three years.

When Hillary Clinton wanted to pair with a pro-life senator to write an op-ed emphasizing “common ground” on abortion, she chose Reid. In the opening line of the 2006 piece, Clinton and Reid identified themselves as “two senators on opposite sides of the abortion debate.”

I don’t think Hillary was supposed to be the pro-life one.

A Reid spokesman insisted to The Weekly Standard in 2009 that the senator “is strongly pro-life” and the spox “resent[ed] any suggestion to the contrary.”

Fair enough. But Reid, whose ratings from pro-life and pro-choice groups have fluctuated wildly over the years, voted with NARAL Pro-Choice America 100 percent of the time in 2012 (though only 70 percent in 2013) but hasn’t voted with the National Right to Life Committee more than half the time since 2003-04.

Reid’s 33 percent National Right to Life rating in 2013 was probably high for a Democrat, but he didn’t vote with the pro-life group a single time in 2009-12, according to their scorecard.

Even Pennsylvania Sen. Bob Casey Jr., who like his late father identifies as a pro-life Democrat and who supports the human trafficking bill with the pro-life language intact, voted with National Right to Life 33 percent of the time in 2014 and 2013, NARAL Pro-Choice America 70 percent in 2013, the last year for which data is available.

There are exceptions. West Virginia Democratic Sen. Joe Manchin voted with National Right to Life 100 percent of the time in 2014 and 2013 after supporting them 23 percent of the time in 2011.

Manchin also went from voting with NARAL 100 percent of the time in 2011 to not siding with them on any scored votes in 2013.

But by and large, the pro-life Democrats’ last gasp came when Bart Stupak led them in capitulating on Obamacare. It’s hard to remember that the pro-life Hyde amendment originally passed in a Democratic-controlled Congress.

W. James Antle III is managing editor of The Daily Caller and author of the book Devouring Freedom: Can Big Government Ever Be Stopped? Follow him on Twitter.