Former Arizona Congresswoman Gabrielle Giffords is set to endorse Hillary Clinton for president, reports Politico.

Giffords has become a major advocate for gun control since she was shot in an Arizona parking lot in 2011. With her husband Mark Kelly, she launched the political action committee Americans for Responsible Solutions. Last week she sat in the front row at President Obama’s press conference where he announced executive actions on gun control.

The endorsement comes as Clinton is attacking her rival, Bernie Sanders, over his record on gun control.

According to Politico:

He often says, “Well look, I’m from Vermont and oh, it’s different, it’s not like being in New York City,” Clinton said on CBS’s “Face the Nation” on Sunday, noting that his Vermont colleague Sen. Patrick Leahy had voted differently. “I think that the excuses and efforts by Senator Sanders to avoid responsibility for this vote — which the NRA hailed as the most important in 20 years — points up a clear difference, and it’s a difference that Democratic voters in our primary can take into account.

The latest Iowa poll has Clinton ahead of Sanders by just 3 percentage points. In New Hampshire, Sanders is leading by 4 percentage points.