Ted Cruz supporters were alarmed Wednesday at suggestions that he was on the verge of endorsing Donald Trump.

They worry that the Texas senator could squander his brand as a fighter — and goodwill earned among many through his stubborn refusal to back his party's nominee — if he caves with nothing to show for it.

Cruz has held out on the grounds that Trump is insufficiently conservative, and because Trump attacked his wife and father down the stretch of their heated battle for the Republican nomination.

The senator even took the extraordinary step of declining to endorse Trump during a televised, prime time speech delivered from the stage of the New York businessman's own nominating convention.

Cruz instead urged Republicans to vote their conscience in November.

After taking such a public stand against Trump, reversing himself this close to Election Day without explaining how he reconciled their ideological and personal differences could damage his future presidential prospects.

"If Cruz were to ever do this, it would be imperative that he describe what changed in regard to Trump's actions that allowed Cruz to finally 'vote his conscience.' And, that's a hard case to make," said Amanda Carpenter, a former Cruz aide who now works as a political analyst for CNN.

Steve Deace, an influential conservative talk radio host in Iowa who endorsed Cruz in the primary, said on Twitter that Cruz risks losing voters' respet.

"...things that kill political brands...Stand tall on principle when it matters most, and then walk away from it for no good reason," Deace said.

The possibility of Cruz backing Trump arose this week.

First, the senator told CNN that he was committed to defeating Democrat Hillary Clinton. Then, Cruz campaign adviser Jeff Roe told Bloomberg News that the senator likes what he's seen from Trump lately and continues to think through his position.

"He thinks about it everyday," Roe said.

Further fueling speculation, the Trump campaign on Wednesday issued a statement in support of Cruz's major push to block President Obama from relinquishing U.S. control of the Internet in favor of an international consortium.

The statement from a Trump policy adviser didn't mention Cruz specifically. But Internet policy isn't something that Trump has discussed on the campaign trail, making it pretty clear that the press release was offered in support of the senator.

Cruz tweeted a thank you to Trump, which appears to be the senator's first communication with his former rival since the GOP convention:

"Appreciate @realDonaldTrump's support of our efforts to keep the Internet free."

Cruz spokeswoman Catherine Frazier declined to comment on the level of any coordination between the Trump campaign and the senator's office, nor on whether Cruz personally asked for the nominee's attempt to insert this policy into a pending budget bill.

Frazier confirmed that Cruz hasn't ruled out endorsing, but declind to elaborate.

For Cruz, whether or not to endorse Trump is complicated.

To begin with, his opposition to Trump is not just ideological. It's also personal.

During the primary, the Trump campaign circulated an unflattering photo of Cruz's wife on social media. Trump himself suggested that Cruz's father was a part of the plot that resulted in the assassination of President John F. Kennedy.

The day after Cruz delivered his stunning convention speech, in which he urged Republicans to vote their conscience, he cited those incidents as among the reasons he was withholding his approval. Trump has never publicly apologized for that behavior.

Yet the Cruz's ideological issues with Trump also matter. Cruz has cultivated the image of a Tea Party warrior who won't compromise what he believes for simple political calculation.

So unless he can show that his endorsement extracted promises from Trump in the way of conservative policies that weren't already on the table at the time of the convention, his backing could look as though it was made out of fear.

That's especially the case since Republican National Committee Chairman Reince Priebus recently suggested that Republicans who don't endorse Trump could face penalties by the party in the future.

And all of that could diminish support for Cruz should he decide to run for president again in 2020, if Trump loses, or beyond.

Cruz's base of support, plus many other "Never Trump" Republicans, were heartened by his willingness to stand up to Trump so publicly. And endorsement without a sufficient reason, could be disappointing, and provide ammunition to his critics who contend the senator is more calculating than principled.

"There were thousands of people not in that arena who will be utterly disappointed that Cruz didn't maintain his principled stand for conservatism," said Rick Tyler, an MSNBC political analyst who served as a Cruz campaign spokesman before being let go because of his role in what was deemed an untrue attack on another candidate.

"Endorsing now for no reciprocation? He would just end up being a Trump Chump," Tyler said.