Sen. Elizabeth Warren (D-Mass.) — economist, Harvard professor and long-time economic-inequality combatant — just endorsed Hillary Clinton. And Friday morning the two are set to meet, fueling suspicion that Warren may be in line to join the Clinton presidential ticket.

But her endorsement and the much buzzed about Friday morning meeting with Clinton will come on the heels of public comments made by two men, both of them fellow Democrats, about Warren's fitness for the office of VP and America's readiness for a hypothetical Clinton/Warren ticket. Let's walk back in time just a few days, before Sen. Jon Tester (D-Mont.) and former Pennsylvania governor Ed Rendell subsequently backtracked on those comments, to examine what they said and what this tells us about the actively evolving state of public thought on women in high office.

First came Tester. The lawmaker told a reporter that Warren is not the right VP pick for Clinton because America is not ready for an all-woman ticket. Tester has since said he didn't mean it, that he spoke with a reporter too soon after disembarking from a train, that the reporter cut him off mid-thought and that he was distracted by an alternative idea. Tester thinks Sen. Sherrod Brown (D-Ohio) would be a good VP on the Clinton ticket. (This would also give Tester, it bears noting, a shot at being top Democrat on the Senate banking committee.)

Make of all of that what you will. Then consider this:

Every president and vice president pair, to date, has been all-male. So, that reality may seem like a norm, the most reasonable and "regular" option. But objectively, it is not. There's no actual reason that two men must lead or even one of them, besides the fact that it has always been that way.

"This campaign makes us confront what we really think about women and women in new roles," said Gayle Lemmon, a fellow at the Council of Foreign Relations and author of the 2015 New York Times bestseller "Ashley's War," a book about an all-female special ops unit.

"When has America ever asked itself the question, 'Should there be two women on the ticket?' " Lemmon said. "But that's where we are. And some of us are very much in the process of figuring out what we really think as this campaign plays out."

Tester's I-don't-know-if-America-is-ready comment sounds just a tad bit like people who say they would date, marry or invite to their home someone from a different racial background if it weren't for the way that their parents, grandparents or step-cousins-in-law would react. There may be truth in those claims, but there's almost always a bit of self-revelation in them, too. At the very least, it's a rationale that says this is an issue on which I am not willing to go to war.

Next up, Rendell, he of the recent ugly-women-will-not-vote-for-Trump commentary (which was also walked back). On Wednesday, Rendell declared that Warren is not VP material because she is not prepared to be commander-in-chief today — and, as such, she should not be nominated as Clinton's vice presidential running mate.

This is one of those statements which, on the surface, may seem totally rational and even gender-neutral. Rendell, the former governor of Pennsylvania, has since said he, too, could not meet his own foreign policy standard — suggesting it's not a gender thing after all.

Presidents do shoulder unique responsibilities on the foreign policy front. They also guide foreign relations and have a hand in when the country engages in military action or deploys or shares its intelligence and military resources. Vice presidents, above all things, must be ready to step in at a moment's notice and do all of these things. And who among us wouldn't say that skill, forethought, preparation and even experience would likely be a good thing.

But, then, all of this raises a serious question: Since when has every vice president, much less every president, arrived on Day One with foreign policy or military experience that might leave them particularly well equipped for this aspect of their jobs? The simple answer is they have not.

Follow us, will you, through the résumé highlights of just some of the nation's four most recent president/vice president teams before they entered the White House.

  • President Obama/Vice President Biden: Obama served as a state lawmaker, then a portion of a term in the U.S. Senate. During his time in the Senate, Obama chaired a subcommittee on the Senate Foreign Relations Committee. Biden, a longtime senator from Delaware, served as chair of the Senate Foreign Relations Committee and the International Narcotics Control Caucus. Before his time in the Senate, Biden served on his area county council.
  • President George W. Bush/Vice President Dick Cheney: Bush served as governor of Texas. Cheney worked as the U.S. secretary of defense during the George H.W. Bush administration, giving him a critical role in the management of wars in each of the Bush administrations.
  • President Bill Clinton/Vice President Al Gore: Clinton served as a two-time governor of Arkansas. Gore was a member of both the U.S. House and Senate, where he represented Tennessee. He was a member of the House Intelligence Committee and the Senate's Homeland Security and Armed Services committees.
  • President George H.W. Bush/Vice President Dan Quayle: Bush served in World War II and in the U.S. House of Representatives, worked as the Nixon administration's U.S. ambassador to the United Nations, U.S. envoy to China during the Ford administration, director of the CIA and was a two-term vice president before he became president. Quayle served in the U.S. House of Representatives and Senate, representing Indiana. Quayle was a member of the House Armed Services Committee.

If we were to continue this list, here's what we would find: Some vice presidents have foreign policy experience or related knowledge. Some have none and were most useful for other reasons, including but not always limited to the state from which they hailed and how many Electoral College votes it had. Some presidents have little to no foreign policy experience and some have a lot. And some administrations with ample foreign policy experience between the president and vice president have made decisions on war and security matters that are widely understood as mistakes.

"It puts us in an interesting place, this election. We have to essentially ask ourselves," Lemmon said, "do we see women and experience through a different lens than we see men and experience? Things we would naturally assume to be part of the conversation about a presidential candidate's qualifications or those of a running mate, we are stepping back and having to all ask ourselves: Are these things I am asking or thinking because this is a woman or because this is really standard or relevant?"