PPP also cited a slight decline for Republican Sens. Dean Heller of Nevada and Rob Portman of Ohio who saw their approval ratings drop by 3 points and 9 points respectively.
Critics of the poll however, say that correlation does not guarantee causation.
For example, Portman's gun vote may have impacted his poll numbers back home, but the last PPP poll was taken in 2012 just after his name had been tossed around to be GOP nominee Mitt Romney's running mate and before he came out in support of gay marriage – the first GOP senator to do so.
"I would urge caution on it. How many people are actually plugged into the gun vote? I would like to see some additional polling," says Kyle Kondik, a political scientist at the University of Virginia. "That is not a diss At PPP, I am just inclined to want to see more information. If it turns out that there is a trend that the gun vote has this much impact, then this would be the best opportunity for gun-control advocates to get another vote, but I think it is too early to tell."