Mayor Bill de Blasio’s job-approval rating has risen to 40 percent and half of New York City voters said they believe he should be re-elected next year, according to a Wall Street Journal/NBC 4 New York/Marist College poll released Wednesday.

Forty percent of registered voters rated him as “excellent” or “good” at leading the city, the poll found. The number is an improvement of 5 percentage points from a poll taken in April.

The results come in the wake of a bombing Sept. 17 in Chelsea that left 29 people injured. Sixty percent of voters polled commended de Blasio’s handling of the incident.

“New Yorkers give the mayor his top grade for his handling of the recent bombing incident in Chelsea,” Lee Miringoff, director of The Marist College Institute for Public Opinion, told NBC 4 New York in a statement.

De Blasio, a Democrat, also has strong numbers ahead of his re-election bid. While half of voters overall said he deserves a second term, 42 percent of Democrats support him in a hypothetical six-way matchup.

“The campaign will continue to remind New Yorkers of the real progress Mayor de Blasio has made,” campaign spokesman Dan Levitan said in a statement, citing de Blasio’s fight against inequality and for affordable housing, lower crime rates and improved police-community relations.

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And despite a multipronged investigation in de Blasio’s fundraising practices, 47 percent of adults said they believe City Hall was fighting corruption while 32 percent said they believe he is contributing to the problem.

Marist College surveyed 1,094 adults, including 799 registered voters, between Sept. 27 and Sept. 29. The margin of error is plus or minus 3.5 percentage points.