Senate negotiations on a bill to squash Obamacare quickly took center stage as Republican lawmakers returned from a 10-day recess.

Vice President Mike Pence called on the Republican-controlled Congress to dismantle Obamacare this summer, so lawmakers can address tax cuts.

“It’s high time we take action,” Pence told a crowd in Iowa this weekend. But Republican Sen. Richard Burr (NC) predicted that it’s “unlikely” the GOP will get a healthcare deal finished this summer.

A House bill replacing the Affordable Care Act narrowly passed in May. But repealing the 2010 health law is looking more challenging in the Senate, where changes to Medicaid and insurance regulations have lawmakers increasingly skittish.