It's always difficult to bring a party together after a hard-fought primary. Kris Kobach hasn't yet succeeded in that task.

Kobach, the secretary of state in Kansas, unseated Gov. Jeff Colyer in last month's primary by just 343 votes. On Tuesday, former GOP U.S. Sen. Nancy Kassebaum endorsed his Democratic opponent, state Sen. Laura Kelly, for governor.

“I’m a Republican, but that doesn’t mean you walk lock-step always with the party,” Kassebaum said.

It's part of an unusual trend this year in which prominent politicians, including three sitting governors, have refused to endorse their own party's picks for governor.

Republicans Rick Snyder of Michigan, Brian Sandoval of Nevada and John Kasich of Ohio have each declined to endorse the GOP nominees to succeed them. In addition, former Illinois Gov. Jim Edgar said Tuesday that he won't endorse Gov. Bruce Rauner, even though they are both Republicans. Edgar described Rauner's Democratic opponent, businessman J.B. Pritzker, as "bright."

Democrats aren't all lining up behind their gubernatorial nominees, either.

In Maryland, Democratic Comptroller Peter Franchot announced weeks ago that he wouldn't endorse former NAACP official Ben Jealous, his party's nominee against GOP Gov. Larry Hogan. More recently, Franchot stated that he won't even cast a vote in the governor's race.

Arizona Congresswoman Krysten Sinema, the Democratic nominee for a U.S. Senate seat, hasn't endorsed David Garcia, a college professor and the party's pick against GOP Gov. Doug Ducey. In both Maryland and Arizona, some Democrats are nervous that their nominees are too liberal to unseat the incumbents.

Few politicians ever go so far as to endorse candidates from the other party. In a polarized era, they may be unhappy with the powers that be within their own party, but they don't have anywhere else to go, suggests Jay Barth, a political scientist at Hendrix College in Conway, Ark.

"In periods in the past, when these faction divides have happened, it would have set the stage for fundamental partisan realignment," he says. "What we see now are encampments within the parties."

Much of the tension this year is on the GOP side. The party, which was split for years between more "establishment" candidates and Tea Party challengers, now faces internal divisions regarding President Trump. While Trump was an outlier in party politics when he began his 2016 presidential run, support for him has become a paramount concern for GOP voters. Trump remains a controversial figure, and at least some Republicans don't support him or the direction in which he's taking the party and the country.

"In 2016, among Republicans, there was a big disagreement within the party of which way to go," says Hans Noel, a political scientist at Georgetown University. "There is a division, and when there is a division within a party, you're not going to get unity, by definition."

For many Republicans running for governor this year, loyalty to Trump was central to their primary message. Not everyone is fully on board yet. That may be especially apparent in Ohio.

Gov. Kasich ran for president against Trump and shows every sign of nursing hopes for a repeat run. In this year's Republican primary for governor, both state Attorney General Mike DeWine, who eventually won, and Lt. Gov. Mary Taylor went out of their way to signal differences with Kasich and allegiance to Trump. Kasich said in May that he will vote for DeWine but not endorse him. That may be a distinction without a difference to many voters, but it signals the incumbent's dissatisfaction, even if he's not willing to fully break ranks.

For others, their lack of endorsement is less about Trump and may be more personal.

In Michigan, Attorney General Bill Schuette not only defeated Gov. Snyder's lieutenant governor in the gubernatorial primary but is prosecuting members of his administration over their handling of the Flint water crisis. For his part, Snyder said earlier last month, "There are a lot of things I want to get done before I am finished. I'm staying out of politics. I'm governing."

In Nevada, Sandoval has consistently refused to endorse Adam Laxalt, the state attorney general and Republican nominee for governor. Last year, Sandoval said he had no interest in supporting someone who wants to undo much of his work.

"Sandoval is very upset that Laxalt wants to repeal his signature achievement, broadening the tax base with a tax on high-grossing businesses," says Jon Ralston, editor of the Nevada Independent. "And he and Laxalt have differed on many issues. Laxalt has embroiled the state in ideological court actions without the governor's signoff."

Laxalt, Schuette and DeWine have all opposed the Medicaid expansion under the Affordable Care Act (ACA). They've mostly softened their stance since winning their respective primaries, but all three of the governors they seek to replace embraced the expansion and lobbied to preserve the ACA in Congress last year.

No state has seen factional warfare within the GOP for as long or as consistently as Kansas. The party remains split between moderates and conservatives who run slates of legislative candidates against each other.

Kobach may not be any more conservative than Gov. Colyer on issues, but he's seen as more combative when it comes to immigration and voting rights issues, and has been closely aligned with Trump, co-chairing the president's failed commission on voter fraud last year.

"There were conservatives like Colyer who don't agree with moderates, but they can play nice with moderates," says Patrick Miller, a political scientist at the University of Kansas. "Kris Kobach not only disagrees with moderates on most key issues, but he is a very different personality, a very different style, and is very confrontational with moderates in Kansas."

Kassebaum, the former senator who endorsed Kobach's Democratic opponent, has a family history of old-school Republicans. Her father, Alf Landon, was the party's presidential nominee against Franklin D. Roosevelt in the 1936 presidential race. After serving three terms in the Senate, Kassebaum married Howard Baker, who had served eight years as the GOP leader in that body.

Her endorsement of Kelly came after more than two-dozen prominent Republicans, including former Gov. Bill Graves, had also announced their support for Kelly.

Kobach didn't hesitate to attack Kassebaum and the others for their apostasy.

“Democrats trot out these same tired has-beens clinging to the past, pretending to be Republicans when they so clearly left the party a long time ago," said Danedri Herbert, Kobach's spokeswoman, on Tuesday.

Four years ago, a group of more than 100 Kansas Republicans, including former legislative leaders, backed Democratic state Rep. Paul Davis in his challenge against Gov. Sam Brownback (who won and was later appointed to an ambassadorship by Trump). Then, as now, they were dismissed by conservatives as retrograde rebels.

“I was surprised at the list of R’s endorsing Rep. Davis," tweeted Doug Mays, then the Kansas House speaker. "I actually thought about 1/3 of them had died.”

After GOP state Sen. Barbara Bollier endorsed Kelly this summer, she was removed from her spot on the Health and Public Welfare Committee. Kansas House Republican Leader Don Hineman then sent an email warning members of his caucus not to follow suit.

“Do not endorse, do not publicly support, do not join a ‘Republicans for ...’ group, and do not write a check,” Hineman wrote. “Any of those actions are very inappropriate for a Republican officeholder. I fear there would be serious repercussions.”

There are lots of Republican legislators who would prefer to see Kelly prevail over Kobach, Miller says, but they won't come out and say so publicly for fear of being stripped of committee chairmanships or other perks and power.

In that sense, it's fair to knock Kassebaum and Graves as yesterday's news. They have nothing to lose since they've long been out of the game.

But their endorsements could still matter. In a red state, Kelly has to struggle to win over every voter who might be wary of a Kobach governorship, especially given the presence in the race of self-funding independent Greg Orman.

"It's important for Kelly to show she's the place to go," Miller says. "They're important for her credibility, particularly for moderate Republicans who need help voting for a Democrat."

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