Veto threat looms over high-stakes talks on terrorism detainees

House and Senate conferees are meeting Monday evening to finalize the Defense authorization bill, congressional sources told The Hill, potentially forcing President Obama to follow through on his threat to veto the legislation.

The White House says provisions in the bill on the military detention of terror suspects would hamper law enforcement and must be changed.

But should Obama veto the bill, as he has promised to do, Democrats could join with Republicans to override the veto and deal the White House an embarrassing defeat. 

An amendment that would have stripped the detainee provisions from the bill failed in the Senate 38-60, while the overall bill passed with a 93-7 vote.

Congressional sources have remained tight-lipped about the high-stakes negotiations over the final bill and aren't providing any clues about what's in store for the detainee measures.

As the conference committee met last week, the White House continued to push for changes to the detainee provisions. The president spoke with Senate Armed Services Committee Chairman Carl LevinCarl Levin'Nuclear option' for Supreme Court nominees will damage Senate McCain's Supreme Court strategy leads to nuclear Senate The Fed and a return to banking simplicity MORE (D-Mich.) about the bill, and other top administration officials met privately with Armed Services members.

Levin and Republicans have so far rebuffed efforts from the Obama administration and Senate Democrats to weaken the military detention policies. Supporters of the detention provisions point to a waiver included in the Senate bill that would allow the administration to move suspects from military to civilian custody, but the White House says it's too inflexible.

Lawmakers are trying to get a bill to the president’s desk before the end of the week amid a slew of legislating Congress is trying to finish before leaving town for the holidays.

With the conference committee close to wrapping up, Democrats opposed to the detainee language are still trying to lobby for changes.

Reps. Hank Johnson (D-Ga.) and Martin HeinrichMartin HeinrichBudowsky: Did Putin elect Trump? This Week in Cybersecurity: Dems press for information on Russian hacks Overnight Cybersecurity: Last-ditch effort to stop expanded hacking powers fails MORE (D-N.M.) circulated a letter this weekend for colleagues to sign onto urging conferees to drop the detainee provisions from the final bill. Sen. Mark UdallMark UdallGardner's chief of staff tapped for Senate GOP campaign director The untold stories of the 2016 battle for the Senate Colorado GOP Senate race to unseat Dem incumbent is wide open MORE (D-Colo.), and Armed Services member who proposed the amendment stripping the detainee provisions, sent a letter to Levin Friday again outlining his concerns.

In addition to terror detainees, the conference committee has a host of contentious issues to resolve when reconciling House and Senate versions of the Pentagon policy bill, including sanctions on the Iran central bank and military chaplains performing same-sex marriages.