NEW YORK (CBSNewYork/AP) -- Mayor Michael Bloomberg is stepping up his gun control campaign by asking donors not to support four Democratic senators who opposed a bill to expand background checks.
Bloomberg's letter to about 1,100 New York City residents comes as his group, Mayors Against Illegal Guns, plans a national bus tour to put pressure on senators who voted against the proposed legislation in April to change their minds.
"Going after these guys and saying 'don't give money to them if they don't vote the way you want' is the way democracy should work," Bloomberg said Wednesday on MSNBC. "You should support the people you agree with and not support the people or work against the people you don't agree with."
The tour leaves Friday from Newtown, where a gunman six months ago killed 26 people, including 20 children, at Sandy Hook Elementary School.
Erica Lafferty, whose mother was the principal of the school and was among those killed, vowed to keep up the pressure as well Wednesday during a conference call with reporters.
Check Out These Other Stories From CBSNewYork.com:
(TM and © Copyright 2013 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2013 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)
for more features.