Gov. Andrew M. Cuomo and New York City Mayor Bill de Blasio said Friday that they would pool state and city money to offer a $20,000 reward to any tipster whose information helps arrest and convict a hate-crime perpetrator.

The offer comes the day after a bomb threat at the Jewish Children’s Museum in Crown Heights, Brooklyn, and another earlier in the week at the Manhattan headquarters of the Anti-Defamation League, a Jewish civil rights group.

The incidents represent the postelection spike in anti-Semitic hate crimes that Cuomo and de Blasio have highlighted for weeks. In several recent cases, callers have disguised their voices and “spoofed” the originating numbers so they appear to be from a different caller.

The announcement represented a rare joint action by de Blasio and Cuomo, fellow Democrats but political foes who hardly ever cooperate on anything publicly. A day earlier, they staged separate solidarity visits to the museum, arriving more than an hour apart.

“As New Yorkers, we stand united in the face of cowardly tactics designed to frighten, disrupt and divide us,” de Blasio said in a written statement.

Cuomo in a statement said the state will continue to work “aggressively” with “federal and local partners to hold those responsible accountable to the fullest extent of the law.”

Reported anti-Semitic incidents in New York City so far this year are nearly triple the number over the same period in 2016, according to the NYPD.

Tipsters can call the state hotline, 888-392-3644, or NYPD’s Crime Stoppers, 800-577-TIPS, or text “HATE” to 81336.

In recent weeks, Cuomo and de Blasio have touted a series of steps to reduce the number of anti-Jewish and other bias attacks and threats in the city, including Cuomo’s proposal to use taxpayer money to secure religious schools and day care centers.