Lansing — A former top adviser to Republican Gov. Rick Snyder is urging him to veto GOP bills that would make it harder to run petition drives and advance proposals to the Legislature or statewide ballot.

Bill Rustem, a Republican who served as Snyder’s strategy director during his first term, joined former Michigan Commerce Director Doug Ross, a Democrat, in an open letter asking Snyder to veto the legislation if it reaches his desk.

The measure was approved by the House last week and is expected to see a vote this week in the Senate. Rustem, who helped lead a 1976 petition drive to create Michigan’s bottle deposit law, told The Detroit News he hopes the bill is stopped or amended before it reaches Snyder’s desk.

The proposal would limit the number of signatures that could be collected from voters who live in any one part of the state, allowing no more than 15 percent from any single congressional district.

“In the U.P. or northern Michigan, that’s going to be very tough,” Rustem said, noting he does not oppose separate provisions that would require petition circulators to indicate if they are paid, as opposed to volunteers. It's the first time he's publicly called on Snyder to veto a bill since he retired from the administration in 2014.

Ross, who also signed the letter to Snyder, served under Democratic Gov. Jim Blanchard and is now a charter school leader. He helped lead a successful 1974 petition drive to repeal the state sales tax on food and medicine.

The Michigan Constitution gives citizens the right to initiate laws through petition drives, and Ross and Rustem said the need to “keep this direct democratic option within reach of our citizens is as great as ever,” especially give the public’s waning confidence in government.

Supporters say limiting the number of signatures that can be collected in any congressional district would ensure voters from more parts of the state would have a say in the process. But in their open letter to Snyder, Rustem and Ross called it an “onerous” provision that would make petition drives more difficult for average citizens.

“You have an opportunity to act upon Lincoln’s injunction to preserve ‘government of, by, and for the people,’” they told Snyder. “By vetoing the legislative to weaken the initiative process should it reach your desk, you would strike a blow for government ‘by the people’ in Michigan.”

joosting@detroitnews.com