Less than one week after politically motivated gunman Robert Dear allegedly killed three people and wounded nine others at a Colorado Springs, Colorado, Planned Parenthood clinic, congressional Republicans moved forward with efforts to strip federal funds from the organization.

Those efforts drew a stern rebuke on the Senate floor on Tuesday from Democratic presidential contender Sen. Bernie Sanders (I-Vt.), who blasted the attempts as part of a political "witch hunt."

"While we still don't have all the details as to what motivated the shooter, what is clear is that Planned Parenthood has been the subject of vicious and unsubstantiated statements attacking an organization that provides critical care for millions of Americans," Sanders said, alluding to attacks on the organization after an anti-abortion group released videos targeting Planned Parenthood this summer. The videos purported to show Planned Parenthood officials offering to sell tissue and organs from aborted fetuses, although claims that the organization profited from the transfer of fetal parts proved unsubstantiated.

Following last week's attack, Dear reportedly told police, "No more baby parts."

In his Senate speech on Monday, Sanders argued that rather than seeking to defund Planned Parenthood, lawmakers should boost support for it.

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Sanders also implored his colleagues to "understand that bitter, vitriolic rhetoric can have serious, unintended consequences."

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"Now is not the time to continue a witch hunt for an organization that provides critical health care services, from reproductive health care to cancer screenings and preventative services to millions of Americans," he added. "No one is forced to seek care at Planned Parenthood. It is a choice, a choice millions of women make freely and proudly."

A national Quinnipiac University poll released Wednesday found that Sanders leads all of the GOP's top presidential prospects, by margins ranging from 1 to 10 percentage points.

You can watch Sanders' remarks on Planned Parenthood here: