The battle over sexu­al as­sault in the mil­it­ary is back.

When the Sen­ate re­con­venes this month, mem­bers will im­me­di­ately dive in­to a le­gis­lat­ive struggle over how the armed ser­vices deals with ac­cus­a­tions of sexu­al as­sault with­in their own ranks. And as it does, two high-pro­file Demo­crats — one a rising star in the party and the oth­er a battle-tested mod­er­ate hold­ing a red-state seat — will re­sume their in­tern­al scrap over the is­sue.

Both New York’s Kirsten Gil­librand and Mis­souri’s Claire Mc­Caskill agree the mil­it­ary needs to change the way it handles as­sault cases, but they have com­pet­ing pro­pos­als on how to do it.

Mc­Caskill’s camp be­lieves that Gil­librand’s plan would ac­tu­ally hurt the ef­fort to fight sexu­al as­sault in the armed forces. And while they com­pete for their pro­pos­als, re­la­tions between the pair have be­come in­creas­ingly tense.

“I’m frus­trated that the re­forms that we have done have not got­ten the at­ten­tion they de­serve,” Mc­Caskill said in Novem­ber of her dis­pute with Gil­librand. “I’m not sure that I’ve done so well at the pub­lic re­la­tions on this; I’ll give that to her.”

In­deed, 2013 saw Con­gress take ac­tion. The Sen­ate’s fi­nal act of the year was to pass the 2014 de­fense au­thor­iz­a­tion act, which in­cluded more than 30 re­forms to ad­dress sexu­al as­saults in the mil­it­ary.

But with the De­part­ment of De­fense es­tim­at­ing 26,000 sexu­al as­saults in the mil­it­ary in 2012, of which only 3,300 were re­por­ted, both le­gis­lat­ors want to go fur­ther.

Mc­Caskill is pro­pos­ing a pack­age of more mod­er­ate re­forms that would in­crease com­mand­er ac­count­ab­il­ity, al­low sur­viv­ors to chal­lenge un­fair dis­charge from the ser­vice, and stop sol­diers from us­ing good mil­it­ary char­ac­ter as a de­fense. The plan is non­con­tro­ver­sial, en­joys broad bi­par­tis­an sup­port, and is ex­pec­ted to be ad­op­ted eas­ily whenev­er it comes up for a vote.

But it doesn’t in­clude one of the most highly sought-after re­forms by vic­tim ad­voc­ates: strip­ping the chain of com­mand of its power to de­cide wheth­er sexu­al as­sault cases are pro­sec­uted.

The Pentagon is staunchly op­posed to that pro­pos­al, but Gil­librand pushed le­gis­la­tion to make the change in 2013 and says she’ll keep fight­ing for it when the Sen­ate re­turns. Sen­ate Ma­jor­ity Lead­er Harry Re­id plans to put the meas­ure on the Sen­ate sched­ule as soon as Janu­ary.

“We are go­ing to have an up or down vote on the bill, prob­ably in Janu­ary,” Gil­librand said in an in­ter­view be­fore the Sen­ate ad­journed. “I will use this in­ter­im time to con­tin­ue to build sup­port. We prob­ably have a dozen un­de­cided sen­at­ors that I’m hop­ing this will give an op­por­tun­ity to make sure they meet with sur­viv­ors from their states.”

Fifty-three mem­bers are pub­licly sup­port­ing Gil­librand. But she is fa­cing an up­hill chal­lenge to se­cure a su­per­ma­jor­ity of 60, which will likely be ne­ces­sary to move the meas­ure through the Sen­ate.

“There is so much ad­di­tion­al in­form­a­tion that has been com­ing out in the last month that I’m hop­ing it provides the time to give that in­form­a­tion to those who are con­sid­er­ing it and weigh­ing it,” she said.

The Sen­ate was ex­pec­ted to vote on both Gil­librand’s and Mc­Caskill’s meas­ures in Novem­ber, but law­makers failed to reach an agree­ment to do so.

Mc­Caskill, who has long worked on sexu­al-as­sault is­sues and is more seni­or than Gil­librand on the Sen­ate Armed Ser­vices Com­mit­tee, has emerged as Gil­librand’s top op­pon­ent in the re­form de­bate. She ar­gues that Gil­librand’s meas­ure will not res­ult in put­ting more per­pet­rat­ors be­hind bars and has taken great lengths to kill her rival’s bill.

As the duo con­tin­ue to duel, groups ad­voc­at­ing for as­sault vic­tims con­tin­ue to push for Gil­librand’s pro­pos­al.

“We’re go­ing to be do­ing a lot of out­reach dur­ing the re­cess in in­di­vidu­al states, ad­dress­ing folks still un­de­cided,” said Greg Jac­ob, a policy dir­ect­or with the Ser­vice Wo­men’s Ac­tion Net­work and a former Mar­ine. “We saw tre­mend­ous suc­cess be­fore the ori­gin­ally sched­uled vote in Novem­ber with six ad­di­tion­al co­spon­sors com­ing in­to the fold after bring­ing sur­viv­ors and com­mand­ers in the field to the Hill.”

Vic­tim ad­voc­ates are also fo­cused on en­sur­ing the re­forms set to go in­to ef­fect un­der the de­fense au­thor­iz­a­tion le­gis­la­tion are im­ple­men­ted ap­pro­pri­ately by the Pentagon.

Un­der the re­forms, com­mand­ers lose the power to over­turn con­vic­tions, or to re­duce guilty find­ings to less­er of­fenses. Min­im­um sen­tences are es­tab­lished for ser­vice mem­bers found guilty of sexu­al as­saults.

Per­son­nel re­cords will in­clude sexu­al of­fenses and re­tali­ation will be­come a crime.

Sur­viv­ors of sexu­al at­tacks will be provided with spe­cial leg­al coun­sel, and will be al­lowed to ap­ply for per­man­ent trans­fers to oth­er units. A five-year stat­ute of lim­it­a­tions for rape and sexu­al as­sault in the mil­it­ary is thrown out. Vic­tims will no longer be al­lowed to be har­assed in pre­tri­al in­vest­ig­a­tions to de­term­ine wheth­er a sexu­al-as­sault case should pro­ceed.

With Demo­crats di­vided over fur­ther re­forms, Pres­id­ent Obama is tread­ing lightly — push­ing the Pentagon on the is­sue without choos­ing a side between Gil­librand and Mc­Caskill.

Obama is­sued a state­ment the day after the Sen­ate passed the sexu­al-as­sault re­forms in the de­fense bill, warn­ing the Pentagon, which is con­duct­ing a re­view due in a year, that ad­di­tion­al re­forms might be ne­ces­sary.

“Mem­bers of Con­gress, es­pe­cially Sen­at­ors Gil­librand and Mc­Caskill, have rightly called at­ten­tion to the ur­gency of erad­ic­at­ing this scourge from our armed forces,” Obama said in a press re­lease.

“If I do not see the kind of pro­gress I ex­pect, then we will con­sider ad­di­tion­al re­forms that may be re­quired to elim­in­ate this crime from our mil­it­ary ranks and pro­tect our brave ser­vice mem­bers who stand guard for us every day at home and around the world.”