The automated calls that began Tuesday are being made in the districts of Dan Benishek, Kerry Bentivolio and Tim Walberg — who Democrats say are vulnerable in 2014. Michigan Reps. Justin Amash and Bill Huizenga are also among 80 House Republicans who urged Speaker John Boehner to resist spending bills accommodating "Obamacare."
Because Democrats reject demands to defund the law, a standoff could result in a partial federal government shutdown Oct. 1.
A Benishek spokesman said he doesn't support shutting down the government. Messages seeking comment were left with Bentivolio and Walberg.