Indiana's Senate race will show the depths of the fault lines within the GOP. Early signs show it's still Trump's party.

• In years past, former Indiana Gov. Mitch Daniels would have been an ideal GOP Senate candidate.
• But this week, Daniels — opposed by social conservatives — announced that he would skip a campaign.

In the Republican Party of the 1990s and 2000s, former Indiana Gov. Mitch Daniels would have been seen by most traditional conservatives as an ideal candidate to run for the Senate.

But after Daniels visited Capitol Hill last week, he announced on Tuesday that he would pass on a Senate bid in 2024, which will be an open seat contest due to Republican Sen. Mike Braun's decision to run for governor.

"After what I hope was adequate reflection, I've decided not to become a candidate for the US Senate," Daniels first told Politico in a statement. "With full credit and respect for the institution and those serving in it, I conclude that it's just not the job for me, not the town for me, and not the life I want to live at this point."

While Daniels, 73, won't be going back to Washington anytime soon, the repercussions of his decision will shape the still-fluid GOP Senate field. Rep. Jim Banks is seen as the early frontrunner for the party's nomination, while Gov. Eric Holcomb remains in the mix as a potential candidate.

Once a GOP ideal

Daniels checks off all the boxes of a top-tier GOP figure: former Senate chief of staff for onetime Indiana Republican Sen. Richard Lugar, former Office of Management and Budget director under President George W. Bush, former two-term governor, and the ex-president of Purdue University — one of the most influential research universities in the state.

During Daniels' 2004 gubernatorial bid, the slogan "My Man Mitch" — an old nickname given to him by Bush — was synonymous with his campaign, which was strongly backed by the then-president. And when Daniels ran for reelection in 2008, his nearly 18-point victory coincided with then-Illinois Sen. Barack Obama's stunning one-point presidential win in the traditionally conservative Hoosier State, a reflection of the governor's strong GOP support and crossover appeal with Independents.

Daniels is in many ways cut from the same cloth as Lugar — who served in the Senate from 1977 to 2013 before his death in 2019 — embracing traditional GOP fiscal conservatism while steering clear of divisive social issues.

His decision that a tough, contested primary was unpleasant, undesirable, or unwinnable points to larger questions: Is there still room in a Republican primary for a candidate like Daniels? And what does Daniels' decision say about the party headed into 2024?

The GOP remains in a 'Trumpified' state

In 2010, when Daniels was eyeing a potential 2012 presidential candidacy, he upset many Republicans when he told The Weekly Standard — the now-defunct conservative magazine — that the next commander-in-chief "would have to call a truce on the so-called social issues" and instead focus on more pressing economic and foreign policy matters.

Daniels — who was succeeded in the governor's mansion by future Vice President Mike Pence — would eventually pass on a presidential bid, citing his family's reluctance to endure such a campaign.

And in January 2013, Daniels would begin a nearly decadelong stretch leading Purdue.

But as the former governor made waves in the halls of academia, Donald Trump burst onto the national political scene, reshaping the Republican Party into one that was less conciliatory and more aggressive in pushing an "America First" philosophy, which disrupted the very international order that had long been embraced by moderates from both parties.

With Trump in office, Indiana Republicans became more powerful — and decidedly more conservative, capturing huge majorities in the state legislature and ousting moderate Democratic Sen. Joe Donnelly in the 2018 midterms.

The ascendancy of social conservatives

As an ally of former President Trump and the onetime chairman of the Republican Study Committee, Banks, 43, is emblematic of the huge sway of social conservatives in Indiana.

Michael R. Wolf, a political science professor and department chair at Purdue University Fort Wayne, told Insider that had Daniels joined the race, he would've had to "fend off the young, up-and-coming" candidacy represented by Banks.

"The fact that Banks could have potentially run someone like Mitch Daniels out kind of indicates — at least in a Republican primary — where things are," Wolf said.

The Club for Growth, the influential conservative nonprofit group, last month threw its support behind Banks' Senate campaign, and also launched an ad discouraging Daniels from entering the race. In the ad, the Club for Growth knocks Daniels' time as Bush's OMB director, accusing him of having "caved in to big-spending Republicans" while showing an image of the former president — a reflection of the no-holds-barred stance of conservatives in the Trump era.

And on Wednesday, Trump himself formally endorsed Banks' Senate candidacy.

Daniels' decision puts other Republicans on notice

While there is certainly no shortage of eager Republican politicians in Indiana, which Trump won by 16 points in 2020, Daniels' decision to skip the Senate race puts a greater spotlight on a potential candidate like Holcomb.

Conservatives appear poised to coalesce around Banks, who is seen as one of their own and would likely be a solid general election candidate in a state that in recent years has taken on a deeper shade of red.

But Holcomb, who was easily reelected to a second term as governor in 2020, has deep ties to Daniels — serving as an advisor to the then-governor and rising to the position of deputy chief of staff in his administration, while also managing the then-governor's reelection campaign in 2008.

When Holcomb in December was asked by the Indianapolis television station WISH-TV about his political plans, he said that he would remain focused on the current legislative session.

"There'll be time for me to think about the future in the future, but it would be next to irresponsible for me to take my eye off the job that I've got," he told the outlet at the time.

Holcomb has compiled a decidedly pro-business record as governor, but in today's GOP, that just isn't enough to win a primary anymore.

Rep. Victoria Spartz — a native of Ukraine who has raised her national profile over the past year as a critic of Ukrainian President Volodymyr Zelenskyy — was mulling a Senate bid but on Friday announced that she wouldn't seek the seat, nor would she run for reelection to the House in 2024.

Indiana could drive the GOP Senate roadmap

Ahead of the 2022 midterm elections, Republicans anticipated making major gains in Congress, which eventually didn't come to pass.

While the GOP did win back control the House, the party has an incredibly slim majority (222-212) in the lower chamber, as Democratic candidates held their own in swing districts across the country last November.

And in the most competitive Senate races, Democratic candidates vastly outran President Joe Biden's approval ratings — which for the past year have largely been mired in the low-to-mid 40s — while also picking up a Senate seat, which gave them a 51-49 majority.

Senate Minority Leader Mitch McConnell of Kentucky last August spoke of "candidate quality" as he explained the unique dynamics of individual races for the upper chamber — while at the same time downplaying predictions of a huge GOP wave.

Although Indiana is poised to back a GOP candidate like Banks next year, Donnelly in 2012 triumphed over the deeply flawed candidacy of then-State Treasurer Richard Mourdock, an anti-abortion conservative who during a debate spoke of abortion in terms that turned off many swing voters.

"I think even when life begins in that horrible situation of rape, that it is something that God intended to happen," he said at the time, while arguing that abortions shouldn't be allowed in the case of rape or incest.

Mourdock was one of several Senate candidates over the past two decades who faltered in winnable races for the GOP, something that McConnell would like to avoid again — if at all possible — next year.

Last week, McConnell met with both Banks and Daniels in Washington, with the congressman telling Politico that he had a "good" meeting with the longtime Senate Republican leader.

But with Republicans still in the minority in the Senate and the potential of Trump once again leading the GOP ticket in 2024, McConnell is surely eyeing the dynamics of the Indiana race even closer.