Despite endorsing Hillary Clinton for president, abortion rights group NARAL Pro-Choice America is disappointed that she and her opponent, Vermont Sen. Bernie Sanders, have yet to be asked about abortion during one of the Democratic debates. NARAL is hoping to change that tonight.

The pro-abortion group has launched a hashtag campaign, #AskAboutAbortion, in an attempt to get the moderators of the sixth Democratic primary debate Thursday to press both candidates on the divisive social issue.

"There have been no questions on the subject in any of the previous debates," NARAL wrote in a statement released Thursday. The group's political director, Joel Foster, penned a letter earlier this week to the two PBS anchors moderating tonight's debate, in which he found "the lack of questions on [abortion] to be shameful and a real disservice to voters."

"The Republican presidential candidates have been asked numerous questions about these important issues in their debates and have been given ample time to express their views to voters," Foster wrote. "We believe it is far past time that Democrats be given the same."

Clinton and Sanders have both called for repealing the Hyde Amendment, a law that currently restricts taxpayer dollars from being used to fund abortions on Medicaid. Last July, after Wisconsin Gov. Scott Walker signed a bill banning abortions after 20 weeks, Clinton described the legislation as "extreme and unacceptable." Sanders, meanwhile, has accused Republican candidates hoping to overturn the Supreme Court's landmark ruling on Roe v. Wade of trying to push an "extreme right-wing agenda."

NARAL, which attracted attention recently for its bizarre tweetstorm during Super Bowl 50, has yet to hear back from PBS, according to a spokeswoman for the organization. The sixth Democratic debate will air live from the University of Wisconsin-Milwaukee at 9 p.m. ET Thursday on PBS News.