Paul Manafort

Paul Manafort, chairman of Donald Trump's presidential campaign, talks to delegates as he walks around the convention floor before the opening session of the Republican National Convention in Cleveland, Monday, July 18, 2016.

(Carolyn Kaster, The Associated Press)

CLEVELAND, Ohio - Here is how not to open your Republican National Convention if you are a presidential hopeful who desperately needs a unifying moment this week.

You don't insult the popular host governor, the Ohio delegates pledged to him, or the many other voters who have given him robust job-approval ratings in a must-win battleground state.

But that is precisely what Donald Trump did.

During nationally televised interviews and a news conference Monday morning, Trump's top campaign adviser, Paul Manafort, unleashed a puzzling attack on Gov. John Kasich. Manafort said Kasich's refusal to endorse Trump, a former rival, is "embarrassing his state." He also criticized Kasich for turning down a no-strings invitation to speak at the Cleveland convention.

This strategy accomplished two things, neither of them positive for Trump. It angered Kasich's allies, many of whom learned of Manafort's remarks while socializing over breakfast with the Ohio delegation. And it reinforced Kasich's resolve to withhold support for Trump.

"Manafort still has a lot to learn about Ohio politics," Ohio Republican Party Chairman Matt Borges said on Twitter. "Doesn't know what he's talking about. Hope he can do better."

Borges, who is hardly a Trump fan, added a few minutes later: "Ohio loves our governor. He turned this state around and united Ohioans. No wonder he has a 60% approval rating."

(A recent Quinnipiac University poll measured Kasich's approval rating at 58 percent.)

Kasich has no plans to enter Quicken Loans Arena this week, but he is in Cleveland visiting with other Republican delegations and helping GOP candidates for the House and Senate. He has vowed not to make mischief for Trump, though he has been open about his disappointment in the presumptive nominee's racially charged rhetoric and divisive approach to politics.

Whatever overtures were made and regardless of whether strings were attached, Kasich's decision not to participate in the convention is not hard to decipher. He wants no part of Trump's coronation here. He says repeatedly that Trump must adopt a friendlier, more-inclusive tone if the New York businessman wants Kasich's help. Trump is nowhere close to doing so.

Conventions, typically low on drama and high on pageantry, are successful if they rally the party faithful and raise their excitement and energy for the fall campaign. Most of the Republican operatives and activists needed to engineer a victory in Ohio are loyal to Kasich. They won't sit this race out just because Kasich is. But they need motivation - not mockery. Everything about Manafort's anti-Kasich rants Monday suggests the Trump team lacks the proper finesse.

"Looking forward to unifying and invigorating our party this week," Manafort said on Twitter.

So far, they are off to a poor start.