“At a time when children being evacuated from daycare centers in response to repeated bomb threats and mosques are deliberately being set on fire, we must ensure that all organizations that face these threats have the support they need,” says the letter to Homeland Security Secretary John Kelly authored by Sens. Roy Blunt, R-Mo. and Kirsten Gillibrand, D-N.Y. “It is simply unacceptable to not act.”

It proposes more than doubling the amount allotted the Non-Profit Security Grant Program from $20 million to $50 million.

Blunt and Gillibrand are this week circulating the letter among their fellow senators, asking them to sign on.

The Orthodox Union in an action alert emailed to its activists on Monday said they should press their senators to join the letter. “Recent threats to Jewish schools, community centers, and synagogues has made the need for additional security measures at our institutions greater than ever,” the alert said.

Unusually, the letter is tailored for each senator who signs it to send it to Kelly individually, with a space left for the senator to list attacks on institutions in his or her home state.

As examples of such incidents, the draft letter lists a fire that gutted a mosque in Victoria, Texas last month and the vandalism in a St. Louis Jewish cemetery, also in February.

The vast majority of funds disbursed under the grant program since its founding in 2005 have gone to Jewish institutions to add security measures, including barriers and video systems. Muslim institutions have only recently expressed interest in accessing the funds.

Jewish groups, spearheaded by the Orthodox Union, the Jewish Federations of North America and Agudath Israel of America lobbied for the launch of the program over a decade ago, and have lobbied to sustain it over the years.

Separately, Sens. Gary Peters, D-Mich., and Rob Portman, R-Ohio, are seeking signatures for a letter that would ask Kelly, Attorney General Jeff Sessions and FBI Director James Comey to apprise the Senate of action that the government plans to take to address bomb threats against Jewish Community Centers and other Jewish institutions. The Orthodox Union sent out an action alert last week urging members to ask their senators to sign on to the Peters-Portman letter.

There have been about 100 such threats since the beginning of the year.