The election is three weeks off, the size of any anti-Trump congressional wave is not precise enough to calibrate, but the look of the next year’s Senate is nonetheless starting to come into view.

Regarded from a high altitude, the north side of the Capitol will retain the same appearance it’s had throughout history. No matter what happens Nov. 8, there’s no getting around a continued oversample of white male senators in middle age or older, meaning the chamber of 2017 will once again look less like America than like the lobby of a venerable law firm from the “Mad Men” era.  

But at ground level, the membership is also poised to undergo a few subtle but important shifts away from its hegemonic past. There may not be any true demographic history-makers in the Senate’s potential Class of 2016, but collectively they are a decidedly younger and slightly more ethnically varied bunch than the members they would be joining.

They are also a more youthful, racially mixed, better educated and closer to gender-balanced group than the incumbents they might be replacing — a sort-of senatorial “wins above replacement player” statistic, to adapt an in-vogue baseball metric.

Barring a late and cataclysmic eruption of the political landscape, no more than 14 states will elect new senators next month — and only 18 challengers or open-seat candidates in those places have a viable shot at winning. These are the potential freshmen. In the main, the measure of additional diversity shaping the Senate will be closely correlated to the size of the down-ballot Democratic surge.

If that party takes over the chamber, it will be with a group of winners who are disproportionately female and not as white as the overall pool of competitive candidates. If the GOP holds control, it will be because the party’s endangered incumbents — seven out of the nine of whom are white men — prove exceptionally resilient.

Another Year of the Woman, maybe

Only one new senator with an outlier biography is a sure thing: Kamala Harris, now California’s attorney general, is a safe bet to secure the seat from which fellow Democrat Barbara Boxer is retiring — and thereby become only the second African-American female senator ever, 18 years after Carol Moseley-Braun lost her bid for a second term in Illinois. (Harris’ father is black and her mother is Indian-American.)

If the Republicans realize their most optimistic dreams, the number of female senators could actually decline to 19, the first drop in that number in four decades. That’s because, while the GOP doesn’t have any viable female Senate aspirants this fall, the other woman who’s retiring, Maryland Democrat Barbara A. Mikulski, is certain to be replaced by a man, Democratic Rep. Chris Van Hollen.

But if a Democratic sweep ends up materializing, the roster of female senators could expand by as many as five, matching the one-election mark set four years ago and creating a Senate that is a record one-quarter women.

Rep. Tammy Duckworth is now a clear if slight favorite to deny Republican Mark S. Kirk a second term in Illinois.  A pair of the tossups feature former Nevada Attorney General Catherine Cortez Masto against GOP Rep. Joe Heck for an open seat, and former Pennsylvania environmental agency head Katie McGinty trying to oust incumbent Republican Patrick J. Toomey. Former state legislator Deborah Ross of North Carolina and, to a lesser extent, Rep. Ann Kirkpatrick of Arizona, remain very much in the hunt against GOP incumbents Richard M. Burr and John McCain respectively.

(The final possible female newcomer, Democratic Gov. Maggie Hassan of New Hampshire, wouldn’t affect the senatorial gender balance because her too-close-to-call contest is against another woman, Republican Sen. Kelly Ayotte.)

Duckworth, whose mother is from Thailand, would also be the second Asian-American female senator ever, joining fellow Democrat Mazie K. Hirono of Hawaii. (Her Indian parentage would also connect Harris to this group.)

Cortez Masto would be the first Latina in the Senate and would bring the number of Hispanic senators to four, assuming Republican Marco Rubio holds on to his slight but clear lead.

Skewing younger and smarter

If the Floridian loses, it would assure the arrival of the Senate’s first millennial, generally defined by demographers as Americans born in the last century who became adults since 2000. The challenger is Rep. Patrick Murphy, who was 16 at the dawn of the millennium.

The second-youngest possible senator next year is a fellow Democrat of the same generation: 35-year-old Missouri Secretary of State Jason Kander, who’s made it a tossup against GOP incumbent Roy Blunt. Seven other potential winners were born in the 1960s or 70s.

(At the other end of the spectrum is Democratic former Gov. Ted Strickland of Ohio, who at 75 would be the oldest person ever to win initial election to the Senate if he scores a still plausible upset against GOP incumbent Rob Portman.)

Still, the average age of the 18 potential freshmen will be 55 years and three months as the 115th Congress convenes — fully six years younger than the average age of the 100 senators at the start of this Congress almost two years ago.

The possible newcomers are also notably better schooled than their would-be colleagues. All except Murphy (bachelor’s in business) have terminal degrees: A dozen are attorneys, three are physicians and two have academic doctorates. Among today’s senators, in contrast, 26 finished their educations with college, 54 have law degrees, three are doctors and just one has a Ph.D.

In other ways, the 18 potential fresh faces have a collective profile that sounds like that of today’s Senate.

A plurality of five candidates are Roman Catholic, half identify with mainline Protestant denominations and two are Jewish, very closely mirroring the existing senatorial faith profile.

And only five of the aspirants have any military service on their resumes, reflecting the accelerating decline of veterans in Congress. Military service, once essential to a smooth political climb, is truly central to the biography of only one potential Senate newcomer: Duckworth, who lost both legs in 2004 when the helicopter she was piloting as an Illinois Army National Guard officer was shot down by Iraqi insurgents.

Finally, the roster of possible new Democratic arrivals is unusual in its crop of familiar faces. There’s a solid shot two former senators will return simultaneously, something that hasn’t happened in 60 years. Russ Feingold of Wisconsin, defeated by Republican Ron Johnson in 2010, is the favorite to win the seat back. Evan Bayh of Indiana, who left voluntarily the same year, is in a tossup against GOP Rep. Todd Young to get the job back.

Ryan Kelly contributed research.