Intraparty fights bruise the frontrunners
One reason for the rising negative numbers for both Trump and Clinton are their intraparty bruises as the primary races become more competitive.
Forty-one percent of Sanders' voters have a negative opinion of Clinton, versus 40 percent who have a positive view of her.
Republicans backing Trump's rivals are even harsher about the GOP frontrunner: 56 percent of Cruz's voters and 71 percent of Kasich's have a negative view of Trump.
"As primaries go deeper, the opposition [becomes] more negative," says McInturff, the GOP pollster.
Overall, however, 73 percent of Democratic voters say they would be satisfied if Clinton becomes the party's presidential nominee (though just 47 percent of Sanders backers say that).
That's compared with 63 percent of Republican voters who would be satisfied if Trump becomes the GOP's nominee, and 66 percent who would be satisfied if Cruz is the Republican winner.
In March 2012, 72 percent of Republicans said they'd be satisfied if Mitt Romney became their party's nominee.