John Bolton is unlikely to drop the bombshell on President Trump hoped for by Democrats should he testify in the Senate impeachment trial, according to those who know him well.

Bolton is a committed hawk who devoted his career inside and outside the government to persuading Republican politicians to adopt his foreign policy agenda. Whatever his opinion of Trump’s conduct with regard to Ukraine, which pushed Democrats to impeach him, Bolton associates are convinced he would not jeopardize his influence with Republicans on national security matters by testifying against the president.

“He’s a national security guy,” said Lisa Spies, a Republican fundraiser who previously consulted for Bolton’s political committees. “That’s his thing.”

Bolton, 71, was U.S. ambassador to the United Nations under President George W. Bush. For years after, he was a regular on Fox News who raised big money from wealthy GOP donors for his political action committee and super PAC. Bolton used the cash to support Republicans who reflected his foreign policy views, donating generously and running television advertisements.

Bolton relaunched his PAC last year after being ousted from the West Wing and immediately announced endorsements and contributions of $10,000 each for five Republican hawks: Sens. Tom Cotton of Arkansas, Cory Gardner of Colorado, and Thom Tillis of North Carolina, and Reps. Adam Kinzinger of Illinois and Lee Zeldin of New York.

Bolstering the Democrats’ case against Trump with damning testimony would immediately blow up Bolton’s post-White House project. With the loyalty Trump commands from the GOP base and most congressional Republicans, donations to his PAC would dry up.

Worse, the relationships that facilitate Bolton's ability to shape Republican foreign policy might be irrevocably broken. Republican insiders who have worked closely with Bolton say his willingness to testify in the Senate, if subpoenaed, should not be misinterpreted as a desire to settle a score with Trump. That is especially true given the president’s strong support for Israel and confrontational policy toward Iran, two major priorities of Bolton’s.

“I’d be surprised if he risked his future in GOP politics and policymaking on testimony that would torpedo the president,” a former Bolton associate told the Washington Examiner.

“His future is about the Republican brand,” a Trump administration official added, requesting anonymity in order to speak candidly. “Bolton cannot toss a Republican president overboard.”

Administration officials who testified in the House impeachment investigation claim Bolton as national security adviser disagreed with Trump’s decision to temporarily withhold $391 million in military aid from Ukraine to pressure Kyiv to launch an investigation into Joe Biden, a top contender for the Democratic presidential nomination. Bolton, according to testimony, referred to the effort, derisively, as a “drug deal.”

The episode forms the basis of the charge of abuse of power article of impeachment against Trump. In early January, after Bolton announced that he would comply with a Senate subpoena to testify in the Senate impeachment trial, Democrats sounded hopeful he would offer evidence that might lead to Trump’s conviction and removal from office.

A majority of Senate Republicans are disinclined to call any witnesses, whether hostile or friendly to Trump.

The president is on track to be acquitted, possibly by all 53 Republicans, and his Senate allies see no reason to introduce unpredictable variables into a highly politicized process. But even if Bolton did testify, some Republicans suspect his beef would be with acting White House chief of staff Mick Mulvaney who, along with Trump’s personal attorney Rudy Giuliani, was a key figure in the Ukraine affair.

“Him and Mulvaney were oil and water,” Sen. Lindsay Graham of South Carolina said. “Mulvaney wants to cut every budget, and Mulvaney’s more like Rand Paul.” Paul, a Republican senator from Kentucky, is a noninterventionist whose foreign policy views are almost the exact opposite of the hawkish Bolton.

A spokesman for Bolton did not respond to requests for comment.