Sen. Ted Cruz wasn’t on any ballot this year, but he might be the biggest loser of this year's primaries.

The conservative firebrand from Texas and potential presidential contender took an unusually confrontational tack when he vowed not to endorse incumbent Republican senators in their primary elections this year. One of the only two candidates he backed also lost.

For Cruz, his uneven strategy might have invigorated his base of conservative supporters, but it won't do him any favors when the 2016 presidential primary comes around.

“He's refused to endorse any incumbents, and he's made a lot of enemies in the caucus,” said one party strategist. Lawmakers from early primary states, such as Sens. Kelly Ayotte of *New Hampshire and Chuck Grassley of Iowa, “may not be up for re-election this cycle, but does anyone think they will lift a finger to help Cruz when he runs?”

As the primary season comes to a close on Tuesday, it's clear that most Republican presidential contenders were content to play it safe. The biggest winner was frequent endorser and 2012 nominee Mitt Romney, who has said he won't run again.

Cruz's strategy was unusual. As Sens. Mitch McConnell, John Cornyn, and Thad Cochran all faced competitive primary challengers, Cruz looked the other way. That burned some bridges with his Senate colleagues in ways that could come back to haunt him in a White House run.

Ayotte confronted Cruz at a Republican meeting last year for working with the Senate Conservatives Fund, a group that has helped fund GOP insurgents taking on incumbent senators. Cruz would likely need Ayotte’s help in New Hampshire, a key early presidential primary state.

Cruz took sides in two open Republican primaries. He endorsed Ben Sasse for Senate in Nebraska, who went on to win, but also picked T.W. Shannon in Oklahoma’s Senate race, who lost in a primary to Rep. James Lankford, the fifth-ranking House Republican.

Most Republicans who navigated the primary endorsement season most successfully were more cautious and tactful than Cruz.

Sen. Rand Paul frustrated some Republicans by endorsing Greg Brannon in the North Carolina Senate GOP primary over Thom Tillis, the favored candidate of national Republicans who ultimately won the nomination. But Paul compensated by endorsing Sen. Susan Collins, R-Maine, who is likely to be re-elected, and Senate Majority Leader Mitch McConnell, a fellow Kentuckian.

Paul’s support for McConnell, who triumphed in a costly primary against Tea Party favorite Matt Bevin, showed that Paul would go to bat for the party, and it might already be paying dividends: McConnell has been a legitimizing figure for Paul to party bigwigs and donors, as Paul has sought to build support for a presidential bid.

But neither Paul nor Cruz endorsed in the Senate primaries that would most often attract attention from would-be Republican presidential candidates: those in important presidential primary states, such as Iowa and New Hampshire.

Rick Santorum and Texas Gov. Rick Perry both did, but they missed the mark by taking a chance on Iowa Senate candidates who fell short in the Republican primary. Sen. Marco Rubio, however, wisely chose to support Joni Ernst, who won her party’s nomination and now stands a solid chance of winning a seat in the Senate over Rep. Bruce Braley, the Democrat.

A few Republicans have opted for a safer path: endorsing former Massachusetts Sen. Scott Brown in New Hampshire, where he is expected to win his primary contest Tuesday with ease, and advance to face Sen. Jeanne Shaheen in the general election. Former Florida Gov. Jeb Bush offered his stamp of approval to Brown, as did Romney.

Romney might be the most successful primary endorser of this election cycle. In addition to endorsing Ernst, Tillis, and Brown, he also correctly picked Republican Monica Wehby to win her primary in Oregon and a handful of Republican House candidates in competitive primaries who came out on top.

Yet, for all the potential rewards of endorsing candidates, some stayed away from the risks endorsement game entirely. Louisiana Gov. Bobby Jindal has yet to endorse even in his home-state Senate race, and has so far only backed Rep. Tom Cotton, R-Ark., who ran unopposed for the GOP nomination for Senate.

As Jindal’s political consultant Curt Anderson reasoned to the Wall Street Journal earlier this year, “One politician endorsing another politician is the most overrated thing there is.”