The popular theory in town is that things are about to get more conservative in the Legislature for the 2015-2016 session. And the statistics back it up.  Based on voting records from the last four years, the numbers point to three key conclusions.

— One, House Republicans who will return to the chamber this session tended to vote more conservatively than those who left the chamber.

— Two, Senate Republicans who will return to the Senate tended to vote more conservatively than those who left the chamber.

— Three, the new GOP leaders who will call the shots on the agenda in Lansing voted much more conservatively than the previous leaders — and they differed on some of the biggest issues of last session.

So if history is any indication, the Legislature is poised to take a step to the right.

Each year, MIRS ranks voting records of all 110 House members on a conservative-liberal spectrum. The higher the percentage ranking, the more conservative the person’s voting was. The rankings are based on dozens of votes the lawmakers cast in the previous year.

Using those rankings from the last four years, MIRS looked at the averages for all the Republicans who served in the Legislature last term.

For the House, the 37 GOP members returning to the chamber — 27 who had four years of rankings and 10 who had two years — averaged a conservative ranking of 72.04 percent.

In comparison, the 22 Republicans who left the House at the end of 2014 — all of which had four years of rankings — averaged a conservative ranking of 70.8 percent.

That’s a difference of 1.24 percentage points.

The divide is wider when you compare the new House Republican leadership to the previous House Republican leadership.

Over the last four years, the 2013-2014 leadership team — the speaker, floor leader, speaker pro tem, whip and Appropriations Committee chair — average a conservative ranking of 68.35 percent:

– Former Speaker Jase BOLGER (R-Marshall), 66.5 percent

– Former Floor Leader Jim STAMAS (R-Midland), 65.25 percent

– Former Speaker Pro Tem John WASLH (R-Livonia), 65.25 percent

– Former Whip Pete LUND (R-Shelby Twp.), 78.5 percent

– Former Appropriations Chair Joe HAVEMAN (R-Holland), 66.25 percent

The Republicans who will fill those positions for 2015-2016 averaged a conservative ranking of 74.0 percent.

– Speaker Kevin COTTER (R-Mt. Pleasant), 78.25 percent

– Floor Leader Aric NESBITT (R-Lawton), 75 percent

– Speaker Pro Tem Tom LEONARD (R-DeWitt), 80.5 percent

– Whip Rob VERHEULEN (R-Walker), 66 percent

– Appropriations Chair Al PSCHOLKA (R-Stevensville), 70.25 percent

As for the Speaker job alone, Bolger averaged a ranking of 66.5 percent over the last four years. Cotter averaged a ranking of 78.25 percent. That’s a 11.75 percentage point difference.

The difference at the top of the chamber is similar in the Senate.

Over the last four years, former Senate Majority Leader Randy RICHARDVILLE (R-Monroe) averaged a conservative ranking of 72.75 percent. New Senate Majority Leader Arlan MEEKHOF (R-West Olive) averaged a conservative ranking of 79.75 percent. That’s a difference of 7 percentage points.

Likewise, the seven Senate Republicans who left the chamber at the end of 2014 tend to vote less conservatively than those who stayed.

The departing GOP senators averaged a conservative ranking of 74.25 percent. But the returning GOP senators averaged a conservative ranking of 77.3 percent.

If the voting trends continue and freshman members vote similarly to returning members, both Republican caucuses will be slightly more conservative next term.

That’s been the assumption of many political watchers in Lansing.

“All you have to do is compare Meekhof to Richardville,” said Bill BALLENGER, a former GOP state lawmaker and founder of the newsletter Inside Michigan Politics.

As for the House leadership, Ballenger said he doesn’t expect Cotter to move to the political middle in his new role as speaker.

“If Cotter is more conservative than Bolger going into the job, chances are he is going to stay more conservative,” Ballenger said. “Because his caucus is going to be conservative.”

On top of that, Ballenger noted that there’s a “wild-eyed troika” of Tea Party-backed Republicans in the House who will be trying to push the caucus further to the right.

The Republicans’ conservative efforts may have already started with both chambers introducing bills to repeal the prevailing wage as their first proposals of the new session (See “GOP Lawmakers Push Prevailing Wage Repeal; Snyder Doesn’t Support It,” 1/15/15).

“It’s almost like they’re throwing down the gauntlet right away,” Ballenger said.

On the differences in voting by House leadership then-and-now, they’re not hard to find.

Cotter, Floor Leader Nesbitt, and Speaker Pro Tem Leonard all voted against Medicaid expansion in 2013. Bolger, former Floor Leader Stamas and former Speaker Pro Tem Walsh all voted for it.

Likewise, Meekhof voted against it while Richardville voted for it.

In 2014, there was a similar difference on a bill to extend the sunset on the 21st Century Jobs Fund, which financially supports economic development programs like Pure Michigan.

Cotter, Nesbitt, Leonard and Meekhof voted no. Bolger, Stamas, Walsh and Richardville voted yes.

On a bill to extend a sunset on the state’s film incentive program, Cotter, Nesbitt and Leonard voted no. Bolger, Stamas and Walsh voted yes. Meekhof and Richardville both voted yes on that proposal.

T.J. BUCHOLZ, president of Vanguard Public Affairs, said he expects both Meekhof and Cotter to be more conservative than their predecessors.

As for the rest of the Republican caucuses, some members may simply be reflecting changes in their districts in their voting. Bucholz said many districts in Northern Michigan are trending more conservative.

And the overall political process, he said, is becoming more polarized — both Democrat and Republican.

“I think prevailing wage is the first salvo of many,” said Bucholz, who noted that Gov. Rick SNYDER vetoed a series of Republican-backed bills on Thursday.

He added, “You may see Gov. Snyder become more of the moderate that people thought they elected in 2010.”