Twenty-one Maine police chiefs and sheriffs – including those in Lewiston, Lisbon, Sabattus and Oxford County – are calling on Maine’s two U.S. senators to vote for two gun safety proposals coming before the Senate Tuesday.

One proposal continues a ban against assault weapons that, without re-authorization, expires in September. The second closes a gun show loophole and mandates that no one can buy a gun without a background check. Background checks are not mandated at gun shows when the seller is unlicensed.

A spokesman for Sen. Susan Collins said Monday she plans to vote for both measures. “Senator Collins had indicated, as has the president, that she would support a straight extension of the ban,” said Elissa Canlass.

Sen. Olympia Snowe, a staunch defender of the Second Amendment who voted against a ban on assault weapons a decade ago, declined to comment Monday on how she would vote. Her spokeswoman said she has “struggled” with the decision.

According to a letter recently sent to both Republicans, a number of Maine police leaders are asking that the assault weapon ban continue.

“The 19 models of military-style firearms prohibited under the ban pose a high risk to our communities. These guns are not necessary for hunting or self-defense, but their light triggers and rapid-fire capability make them weapons of choice for criminals,” according to the letter, released by Americans for Gun Safety.

Since the ban was implemented in 1994, the proportion of crimes traced to assault weapons has dropped by more than 65 percent, the letter stated.

The letter also said the current gun show loophole allows criminals to buy firearms because background checks are not required. The Bureau of Alcohol, Tobacco and Firearms has found that gun shows are the second leading source of firearms recovered in illegal gun trafficking investigations, according to the letter.

Police officials signing the letter include David Brooks of Lisbon, Michael Chitwood of Portland, Cumberland County Sheriff Mark Dion, Thomas Fales of Sabattus, Oxford County Sheriff Lloyd Herrick, Lewiston Chief William Welch, Bangor Chief Donald Winslow and Kennebec Sheriff Everett Flannery.

bwashuk@sunjournal.com