Advocates are stepping up their Capitol Hill lobbying efforts to prevent a ban on city-funded abortions, as a Senate panel prepares to consider the spending bill that funds the D.C. budget for 2012.

The House-passed version of the measure, which also funds the Treasury Department and a host of other government agencies, includes a ban on having the District use its own taxpayer funds to pay for abortions for low-income women. That prohibition, supported by Republicans and anti-abortion groups, drew sharp complaints from House Democrats and the White House, which said it “undermines the principle of states’ rights and of D.C. home rule.”

Activists now hope to keep that and other potential social policy “riders” off the Senate version of the bill, which will be marked up by an appropriations subcommittee Wednesday and then the full Appropriations Committee on Thursday. The draft bill has not been released, and even if it does not include the abortion ban, a Senator could propose an amendment to add it this week.

On Monday, the co-chairwomen of the Congressional Pro-Choice Caucus — Reps. Louise Slaughter (D-N.Y.) and Diana DeGette (D-Colo.) — sent a letter signed by 59 lawmakers to House and Senate Democratic members of the appropriations panels urging them to stand firm against a ban in the final version of the spending bill.

“The autonomy of the District is necessary for democratic self-governance, and Congress should be mindful not to violate District residents’ rights to control their own tax dollars,” the letter says. “By failing to permit the District of Columbia to spend local government funds on abortion, we are sending the message that low-income women should not have access to the same medical services that middle- and upper-income women can access.”

The District has already lost on the abortion issue once this year, as President Obama cut a deal with Republicans in April on a spending resolution that included the ban. Calling that bill a “devastating blow,” Del. Eleanor Holmes Norton (D-D.C.) warned in a press release Tuesday, that “we cannot allow a repeat in 2012.”

Separately, the advocacy group DC Vote has been running what it calls ”Operation Illinois and Louisiana” — asking residents in those states to contact Sens. Mark Kirk (R-Ill.) and Mary Landrieu (D-La.), two moderate members of the Appropriations Committee, and urge them to vote against any riders on the District spending bill.