"After stop 5 of 11, I'm not sure how any Member of Congress could support military action in #Syria," he tweeted. "Never witnessed something so unpopular."
Amash reported oversized crowds in Michigan during his first day of talking to people about Syria.
"So many ppl at 3rd stop of 11 that we had to move to parking lot," he tweeted earlier. "I can't recall issue this lopsided. Ppl do not support strikes in #Syria."
In earlier tweets, he warned House Speaker John Boehner (R-Ohio) that he is hearing "almost unanimous opposition" to military strikes. Earlier today, Boehner said he would support the administration's request.