MILWAUKEE — Gov. Scott Walker said Tuesday he was comfortable with expanding Wisconsin's school voucher program slowly, and he also stands by the agreement he and Republican lawmakers reached about the program's future growth.

Walker said the voucher program will expand as long as it shows improvement. Succeeding on a small scale would show how well the program works, he said, making it easier to justify expanding even further.

"The ability for us in two years to come back and make the case to expand beyond what we're doing initially throughout the rest of the state will be largely dependent on what the public sees," he told members of School Choice Wisconsin, a pro-voucher group. He added later, "In the end results matter."

Walker's initial budget proposal would have expanded vouchers to nine districts, with no enrollment limit after the second year. But he reached a compromise with GOP lawmakers that would expand the program statewide and impose enrollment limits everywhere except in Milwaukee and Racine.

Vouchers allow students to attend private and religious schools with a taxpayer subsidy. The deal included in the budget would increase the value of vouchers and tie future increases to the funding that public schools get.

The compromise deal drew criticism on both sides, from advocates of public schools who don't want vouchers expanded statewide and by voucher supports who don't want a cap on enrollment.

The deal was added to the state budget last week. The Senate and Assembly must pass identical versions of the budget before it heads to Walker's desk.

After Walker's speech, reporters asked whether he might use a line-item veto to cross out the budget language that imposes the cap. Walker said he usually doesn't comment on veto plans because the bill could still be changed before it reaches his desk. But he signaled that he supported the current form as is.

"We got an agreement and I don't see any changes that would tie into that agreement," he said.