Wisconsin Gov. Scott Walker to Republicans: 'Put up or shut up'

Wisconsin Gov. Scott Walker had some advice for the GOP on Friday: put up or shut up.

The words from Walker, a Republican, followed remarks made Thursday by Treasury Secretary Steven Mnuchin to CNBC regarding tax reform and his "aggressive" August timeline.

When asked how the Republicans could avoid any potential problems, Walker told CNBC's "Squawk Box" they had to deliver on their campaign promises.

"The biggest thing I would say is what I said six years ago after we went from all-Democrat to all-Republican control in our state. I said it's put up or shut up time — meaning the voters wanted a change. They spoke loud and clear, and if we just nibbled around the edges, I told the new Republican majorities that time in our state legislature, they'd be right to throw us out two years later," Walker said.

Walker noted that Republicans have to concentrate on their constituents.

"It's real easy, particularly in a town like Washington, D.C., to get caught up in the noise ... the reality is that people outside of this city — and I call it 'Washington, D.C., 68 square miles surrounded by reality' — there are real people across America who want Republicans to do the things they've said during the campaign, who aren't at protests, who aren't showing up at town hall meetings," said Walker.

He said Republicans have to focus on lowering the corporate tax rate to boost competition with the rest of the world and bringing more jobs back to America.

"They do those two big things, rein in regulations on top of that, we're going to have a thriving economy, which will — more important than helping us in the 2018 midterm elections — it'll help this country," Walker said.

However, Harry Stein, director of fiscal policy at the Center for American Progress, said he had some reservations about Mnuchin's tax plan and who it will benefit.

"For all the talk about Trump being very different than Republicans, and he may be in some respects, but when it comes to tax cuts for the wealthy, this is the same trickle down economics that we've been hearing for decades," Stein said on "Squawk Box."