Sen. Bob Casey (D-Pa.) is not generally considered especially vulnerable in this year’s election, and a Morning Consult poll  released Thursday suggests he has a net approval rating of 8 percentage points.
Yet when asked if he deserves re-election, only 30 percent of Pennsylvania voters said “yes,” compared with 45 percent who said it was time for a new person.
The story is similar for 11 Senate incumbents facing re-election. Even those who get relatively high approval ratings face electorates seeking change. Since 10 of those 11 incumbents are Democrats, it presents a possible warning sign in a political environment that otherwise is shaping up as quite favorable for the party.
The survey of 275,000 voters, conducted February through March, indicates that President Donald Trump’s overall approval rating stands at 42 percent, and voters across the country favor an unnamed Democrat to an unnamed Republican by a 5-point margin.
But the story is different in the dozen states likely to determine control of the Senate. In those states, Republicans win the so-called generic ballot by 3 points or more in six states, all but one held by Democrats. Democrats have a clear advantage in just two states — Virginia and Wisconsin. And the partisan advantage is within 3 points in the other four states.
The picture is bleakest for Democrats in Missouri and West Virginia, where more voters disapprove than approve of their incumbent Democratic senators.
“A new poll from Morning Consult shows that Sen. McCaskill is more unpopular than ever,” tweeted Missouri Rising Action, a super PAC supporting Republican candidate Josh Hawley.
Beyond Missouri and West Virginia, however, political experts downplayed the significance of results showing a plurality of people want someone new.
Terry Madonna, a political scientist and pollster at Franklin & Marshall College in Pennsylvania, said the approval rating of all the state’s political candidates have taken a hit because of a string of public corruption scandals.
But Madonna added that Casey is a well-known commodity who likely does not have much to worry about in November.
“The issue for Casey is simple. He’s won five statewide elections straight, four by double digits,” he said. “Casey’s election is going to be a referendum on Trump.”
[lz_table title=”Vulnerable Senate Incumbents?” source=”Morning Consult”]Many voters say it is time for a new senator
* Favors someone new
** Deserves re-election
If this proves true, the Morning Consult poll suggests an uphill battle for the likely Republican nominee, Rep. Lou Barletta. Trump is 6 points underwater in the Keystone state.
Of the 12 states with potentially competitive races, Trump is above water only in West Virginia (by 23 points), Montana (4 points), Missouri (3 points) and Arizona (2 points).
Christopher Devine, a political science professor at the University of Dayton in Ohio, said the most important measures of incumbent vulnerability are the quality of challengers that they draw and head-to-head poll results involving the actual candidates.
Voters like to register dissatisfaction with the political system when asked questions without naming opponents, such as whether they think it is time for someone new, Devine said.
“They tend not to act on it … It’s sort of people venting,” he said.
Like Casey in Pennsylvania, Ohio’s incumbent Democratic senator, Sherrod Brown, generally is considered relatively safe. The Morning Consult poll gives him a 45 percent approval rating, compared to 29 percent who disapprove.
But by a margin of 42 percent to 32 percent, Ohio voters favored “time for a new person” over whether Brown deserves re-election.
“When you get to specifics, when you get to actual choices, that hunger is not as strong,” Devine said.
History offers strong evidence of a blue wave in November. Trump’s approval rating is low, Republican retirements are high, and Democratic voters are showing more enthusiasm.
Those factors seem to be much more salient than poll results showing that voters want changes in their Senate representation, Devine said.
“But the rules seem to be changing somewhat,” he added. “Who knows?”