Fewer podiums, more-moderated moderating and a few welcome policy contrasts marked an occasionally plodding but certainly more substantive fourth Republican presidential debate.

The separation into candidate tiers was evident again Tuesday night in Milwaukee. Unlike Boulder, Colorado, the emphasis was less horse race and more dash to score governance points.

This left one of two outsider co-front-runners, Ben Carson, mostly out of range. Fellow outsider Donald Trump displayed stylistic improvements but remained typically sketchy on substance.

Which provided the opening that back-in-the-pack runners Jeb Bush and John Kasich needed to whack away at Trump’s simplistic solutions to the nation’s immigration impasse. Trump reiterated his desire to wall off the Southern border and send home any undocumented immigrants left on the U.S. side.

This “makes no sense,” Kasich correctly noted. “We all know you can’t pick them up and ship them … back across the border,” he said. “It is a silly argument. It is not an adult argument.”

Bush, coming off a dreadful debate last month, was closer to the top of his game, with Trump a handy foil. “Sending 11 million people back is not possible, and it’s not embracing American values,” the former Florida governor said. “Even having this conversation sends a powerful signal. They’re doing high-fives in the Clinton campaign over this.”

(Seconds later, thanks to Twitter, we got confirmation from Hillary Clinton’s spokesman.)

“We actually are doing high-fives right now,” Brian Fallon tweeted.

The back-and-forth lays bare a significant fault line for Republicans in 2016. The further right candidates drift on immigration — as in Trump and Sen. Ted Cruz of Texas — the more they risk alienating Latino voters. The Catch-22 for Bush and Kasich is that the Republican base already is solidly to their right. What might play a year from now will hurt more than it helps in landing the nomination.

Similarly, Kentucky Sen. Rand Paul, roused from a campaign stupor, offered a defense of his libertarian leanings and specific criticism of Florida Sen. Marco Rubio for backing enhanced defense spending at the expense of smaller-government conservatism.

“Marco, how is it conservative to add a trillion-dollar expenditure to the federal government that you’re not paying for?” Paul said. “Can you be a conservative and liberal on military spending?”

Rubio’s response: “Yes, I believe the world is a safer — no, I don’t believe, I know — the world is a safer and better place when America is the strongest military power in the world.”

It’s another legitimate governance question for a general-election audience, but it puts Paul solidly to the left of the average Republican voter.

While the focus on actual policy differences was refreshing, it did not shake the overall dynamic of this crowded race. And only two GOP debates remain before voters take over in February with the Iowa caucuses and New Hampshire primary.

— The Dallas Morning News, Nov. 11