Some states are moving to limit abortion coverage under the Affordable Care Act. (Chris Greenberg/Bloomberg News)

Days before lawmakers must pass new legislation to fund the government, Republicans are vowing to reject any proposal that includes public money for Planned Parenthood. The move could trigger not only a shutdown, but if it succeeds, more bills for taxpayers.

The Congressional Budget Office said in a new report on Thursday that cutting off the women’s health organization from federal money would actually increase public spending by an estimated $130 million over 10 years.

Planned Parenthood, which receives about $500 million annually from the government, was hurled into the spotlight this summer after an anti-abortion group released several videos showing employees discussing the logistics of fetal tissue donation and reinvigorated the national debate over abortion.

Recent proposals from Republicans, including one that passed the House last week, would halt funds for just a year. Senate Republicans proposed a similar measure Tuesday, which is expected to fail in a vote on Thursday.

Planned Parenthood supporters, defending the organization on the streets and with hashtags, now wait to learn the fate of its primary source of funding. Eighty percent of clients receive “services to prevent unintended pregnancy,” according to the organization's data, though federal funding is not permitted to be used for abortions.

“This legislation threatens millions of people's access to preventive health care,” Planned Parenthood president Cecile Richards said Thursday in a statement. “In their obsession with attacking women’s access to health care, extreme members of Congress would take basic health care away from people who need it most --- those who are struggling to get by, who rely on Medicaid or have no health insurance, and those who live in areas with few medical options.”

The centers serve more than 40 percent of women who receive birth control from safety-net providers in 18 states, according to a recent report from the Guttmacher Institute, a nonprofit reproductive health organization,  and more than half of such women in 11 states.

The CBO, a nonpartisan watchdog, estimates defunding Planned Parenthood, which serves roughly 2.6 million women, would lead to more unplanned births as patients lost access to birth control. Medicaid would cover some of those births, the report asserts, and some of those children would qualify for Medicaid and other welfare programs.

The office’s math: Halting federal funds to Planned Parenthood would shrink spending by $520 million in the short run -- but, over the first decade, it would cost taxpayers an additional $650 million.

“The effects of the legislation on federal spending are highly uncertain,” the report said, and would depend largely on if and how Planned Parenthood clients sought alternative services.