It’s not surprising that Elizabeth Warren is withholding her endorsement of Hillary Clinton for president. Warren is a megastar in her own right, and her support carries more weight than the other 13 Democratic women senators who endorsed Clinton last month. Warren also declined to squander her box-office appeal by joining Clinton’s “Massachusetts Leadership Council,” announced this week, where she would have been one of many since the rest of the state’s Democratic delegation is on the list.

It is not personal, it’s business, although before she became a senator Warren was quite critical of Clinton’s relationship with the financial industry. And depending where you sit, and how paranoiac you are, Warren is courageously carrying the flag for the 99 percent as the sheriff for Wall Street, pushing Clinton to the left, or she’s secretly hoping Bernie Sanders wins the New Hampshire primary and a panicked party drafts her into the race as the more electable progressive voice.

Either way, there’s no evidence that Warren’s refusal to endorse signals a progressive revolt. Clinton has methodically built support from leaders across the country and from a majority of the left-wing Congressional Progressive Caucus. And while Sanders embodies her anti-Wall Street message and would love her support, she’s not aligning with him, either.

“She’s just focusing on maximizing her own voice,” says former Massachusetts Congressman Barney Frank, who praises Warren for sticking to the financial and consumer issues that she most cares about after all the media frenzy over whether she was running for president. “She’s made the very correct decision to be enormously influential as a senator in the minority, and she’s not going to dilute her impact on public policy.”

For the record, Frank supports Clinton for president, and when I suggested the left would love to see Warren as Treasury Secretary in a Clinton administration, he forcefully rejected the idea.

“Why go to work for somebody else? She’s one of the most influential senators in American history. How many Treasury Secretaries have been influential? Why work for somebody else? She’s more influential on her own. She doesn’t get into all kinds of issues. She has her views on foreign policy and the environment, but she’s focused on what she knows the best.”

That’s high praise for a freshman senator, and while Warren is in no apparent hurry to endorse Clinton, she did send the Democratic frontrunner a kind of digital bouquet Monday with a Facebook post praising Clinton’s proposals to regulate Wall Street. “Secretary Clinton is right to fight back against Republicans trying to sneak Wall Street giveaways into the must-pass government funding bill,” Warren wrote.

In an Op-Ed published Monday in The New York Times, Clinton defended the Consumer Financial Protection Bureau against GOP attempts to weaken or defund it. The CFPB was Warren’s brainchild and she once hoped to head the agency. “Whether it’s attacking the C.F.P.B., undermining new rules to rein in unscrupulous retirement advisers, or rolling back any part of the hard-fought progress we’ve made on financial reform, she and I agree,” Warren declared.

The absence of Warren’s name from the Massachusetts Leadership Council shouldn’t worry Clinton. “She’s become a Democratic star, and you give a star an individual opportunity,” a veteran Hill staffer said. Warren’s endorsement could be more valuable later in the process if Donald Trump continues to garner populist support. Warren was out front with a populist message before Trump appeared on the scene, and could be a valuable ally down the road to help Clinton drown out Trump.

The two women sat down together one-on-one last December, and Clinton subsequently met with economic experts that Warren recommended. Aides in both camps said they didn’t know of any additional contacts, and there is wariness on both sides of saying or doing something that might produce negative stories about their relationship.

That’s probably because they don’t appear to have much of one, and a natural suspicion of one for the other manifests itself in their aides and supporters. A longtime Clinton backer who met with Warren recently on a foreign policy matter found her perfectly pleasant but not that well-informed, prompting him to brand her “a one-trick pony (consumer interests).”

That’s what Barney Frank loves about her, that she sticks to the issues she knows, and where she can make the most difference. If Clinton reaches the White House, Warren could be her wingman, and the seeds of that relationship should be sown in the battlefield of a campaign. Then again, the longer Warren waits to endorse Clinton and the safer it is for her politically, the less appreciated it will be by the Clinton folks. And if Clinton wins New Hampshire without Warren’s endorsement, it could be Elizabeth Who?