Leave it to Congress to mix abortion politics into a largely non-controversial debate about human trafficking.

But here we are.

Abortion politics are threatening to torpedo a popular bipartisan bill to counter trafficking, and in the process further stall and maybe even sink the nomination of Loretta Lynch as attorney general.

A first test comes Tuesday when the Senate votes whether to debate the anti-human-trafficking bill. Expecting to fall short of the filibuster-proof 60 by one or two votes, Republican leader Mitch McConnell over the weekend played what he thinks is his ace card: Loretta Lynch.

McConnell said he wouldn’t call a vote to confirm Lynch until the Senate finishes its work on the trafficking bill, in effect holding Lynch hostage to an obscure anti-abortion provision that was added by the GOP, and that went unnoticed by Democrats until pro-choice groups pointed it out.

Though the stalled legislation and the Lynch confirmation haven’t gotten as much attention as the standoff over funding the Department of Homeland Security, the dynamics are similar.

“I don’t see how the Democrats can back down,” says Matt Bennett, a co-founder of Third Way, a centrist Democratic group. “Only one side can back down. I just don’t know when.”

Denying a well-qualified nominee who would be the first black woman to be attorney general makes no sense when Republicans prefer Lynch to Eric Holder, and when they risk inflaming racial politics by blocking her.

Even so, says Bennett, “Her race is not likely to become a major issue. It’s more about their inability to govern.”

Lynch—who has been confirmed twice by the Senate for her post as U.S. attorney in New York—has been waiting for a vote for more than four months.

That’s the longest anyone has waited in three decades for a key Cabinet position.

White House Press Secretary Josh Earnest in his Monday press briefing called it “unconscionable.”

When McConnell assumed the leadership, he promised no government shutdowns, and that the GOP would get things done.

He barely avoided a shutdown over DHS funding, and now he’s found himself yet again in a box of his own making.

And, as usual, the argument has devolved to partisan bickering.

Democrats say Republicans violated the gentlemen’s agreement between staffers from opposing parties: When the majority makes changes or additions to a bill, the minority is informed.

Instead, Democrats say, Republicans inserted a provision in the trafficking bill that would make an anti-abortion measure known as the Hyde Amendment permanently disallow fines collected from traffickers to pay for abortions sought by their victims.

Originally passed in 1976 in response to the Supreme Court’s legalization of abortion, the Hyde Amendment banned taxpayers’ money from paying for abortions for women receiving Medicaid.

It’s never been permanent law, yet it is customarily re-authorized every year.

In 1993, after the Clinton administration took office, rape and incest were added to life and health of the mother as exceptions.

A source familiar with the language in the trafficking bill, and who supports it, concedes that the victims of trafficking likely could claim rape, and the language could be moot.

Yet, it is still fodder for another major standoff between the two parties. Republicans are right when they say the Hyde Amendment language is routine, but it is typically attached only to appropriations bills, and it’s not permanent; it must be renewed annually.

Four Democrats are expected to join 54 Republicans in Tuesday’s vote to debate the trafficking bill: Bob Casey of Pennsylvania; Joe Manchin of West Virginia; Heidi Heitkamp of North Dakota; and Joe Donnelly of Indiana.

The anti-abortion language slipped into the trafficking bill is “appropriations gobbledygook,” says Jim Manley, Democratic leader Harry Reid’s former spokesman, even as he concedes Democratic staffers should have thoroughly read the 63-page bill and spotted the offending words.

It wasn’t until pro-choice groups saw it that the issue took on a life of its own and a bill certain to win broad bipartisan support became an albatross for McConnell.

“Leaving aside how it got in there, if Republicans really wanted to get this bill passed as they claim, they would just drop this language knowing it’s highly objectionable to Democrats,” says Manley.

That option is open to McConnell, though it would be at great political cost to his standing with the base of his party. McConnell is trying to cast Democrats as the obstructionists, and he’s “made the calculation there are no political losses, that it’s an inside-the-Beltway drama, starring McConnell and Reid,” says Manley. “McConnell will spend a couple days talking about it, see if any Democrats are feeling the heat, and meanwhile Eric Holder is still sitting there.”

Democrats lost the debate about the Hyde Amendment 40 years ago, and they’ve been fighting a rear-guard action ever since.

Named after the Republican congressman who crafted it, Henry Hyde, its ban has been restricted to taxpayer funds, and extending it to cover fees collected by the government, and making it permanent, takes it to a whole new level.

“It’s not like pro-choice activists can look to the Supreme Court for help or protection anymore,” says Manley.

So what does this have to do with Lynch? Nothing.

So Congress is the battleground, and Lynch the collateral damage.