Sen. Kelly AyotteKelly AyotteRNC chair warns: Republicans who refused to back Trump offer 'cautionary tale' OPINION: Democracy will send ISIS to the same grave as communism Kelly Ayotte joins defense contractor's board of directors MORE (D-N.H.) has lost support due to her vote last week against a gun control bill, according to a new poll. The dip could put her at the top of target lists for pro-gun-control groups looking to sway votes on a future measure.

According to the survey, from Democratic firm Public Policy Polling, 50 percent of respondents said her vote against the measure to expand background checks, which failed in the Senate last week, would make them less likely to support her for reelection.

Ayotte joined most of her Republican colleagues, as well as four Democratic senators, in helping defeat the bill.

About a quarter of respondents said her vote made them more likely to support her, and another quarter said it made no difference in their support.

The vote, unsurprisingly, hurt Ayotte most among Democrats, with 79 percent of Democrats saying it made them less likely to support her. Fifty percent of independents and 17 percent of Republicans said the same.

In a state where a plurality of voters declare no party affiliation, and one that leans blue, Ayotte's loss of support among independents could be problematic looking toward reelection in 2016.

Her approval rating has taken a sharp hit from centrists since the last PPP poll of New Hampshire, in October. Then, centrists were split on the senator, with 41 percent approving and 40 percent disapproving of her job performance.

Now, she's deep underwater with centrists, with only 30 percent approving and 61 percent disapproving. Overall, respondents were largely split on Ayotte, with 44 percent approving of her job performance and 46 percent disapproving.

Current Democratic Gov. Maggie Hassan also leads Ayotte in a hypothetical 2016 match-up, taking 46 percent support to Ayotte's 44 percent support.

The poll is the first clear indication that a blue-state Republican could see electoral ramifications for votes against gun control. And there's early indication she could be a top target for gun control groups looking to sway senators on a future vote.

She is one of the first senators targeted by the group backed by former Arizona Rep. Gabrielle Giffords, which launched its first post-vote ads on Wednesday targeting Ayotte and Senate Minority Leader Mitch McConnellMitch McConnellTrump quietly putting his stamp on the courts Democrats see ObamaCare leverage in spending fights OPINION | Progressives, now's your chance to secure healthcare for all MORE (R-Ky.).

The poll was conducted among 933 New Hampshire voters from April 19-21, and has a margin of error of 3.2 percentage points.