GEOFF BENNETT: Split-ticket voters -- those are people who vote for candidates from different parties -- are increasingly rare in modern American politics.

But, as Lisa Desjardins explains, those that cross the aisle on their ballots this November may decide which party controls the U.S. Senate next year.

COLIN PASCAL, Democrat: We can't work all the time.

We have to do something to take our mind off things.

LISA DESJARDINS: In Annapolis, Maryland Colin Pascal is still learning the ropes of sailing, picking it up after retiring from a 20-year career in the Army.

COLIN PASCAL: Sailing is incredible because it's one of the few times that you can have motion without noise.

LISA DESJARDINS: Motion without noise, it's not a big leap to see that as a political metaphor as well.

COLIN PASCAL: By disposition, I would like all of us to move forward with less yelling.

LISA DESJARDINS: He's charting another new course this November, splitting his ticket between Democrat Kamala Harris for president and, for Senate, the first Republican ever to win his vote.

COLIN PASCAL: I'm a registered Democrat.

I have been a Democrat my entire life, and I'm voting for Larry Hogan, who's the Maryland Republican candidate for Senate.

LISA DESJARDINS: Why?

COLIN PASCAL: I really do think we're at our best when the center-left and the center-right are pulling on each other a little bit and we find a workable solution in the middle.

LISA DESJARDINS: Larry Hogan is a dream recruit for Republicans, a popular moderate and former two-time governor in a blue state, part of a GOP on offense.

Senate Republicans need to pick up two Senate seats to take over the chamber outright and just one to create a 50/50 tie, which would break in favor of the party that wins the White House.

They have a good map.

Of the 34 Senate seats on the ballot, Democrats are defending a whopping 23 of them.

One of those, West Virginia, is expected to flip to Republicans.

And seven other Democratic seats across the country could go either way, meaning Democrats have no room for error, no room to worry about a bright blue state like Maryland.

But Hogan is a recognizable force, stopped constantly while campaigning at the state fair.

FMR.

GOV.

LARRY HOGAN (R-MD), Senatorial Candidate: It's so nice to meet you.

LISA DESJARDINS: He won nearly a third of Democrats in his 2018 election.

Hogan is anti-Trump, key in a state that voted for Biden by 33 points.

He needs voters like Colin.

COLIN PASCAL: I'm trying to get every veteran and every Democrat in the state for you also, because I'm both of those things.

FMR.

GOV.

LARRY HOGAN: Well, we just got to convince some of those Democrats who already liked me and voted for me twice.

It's all about those ticket-splitters.

LISA DESJARDINS: But... PIER BLAKE, Democrat: My first question about Hogan was, well, why would he want to run for Senate?

LISA DESJARDINS: ... Pier Blake will not be ticket splitting this time.

The Maryland resident works as a nonprofit executive.

She voted for Hogan in 2018, appreciated how he handled the pandemic and that he sent the National Guard to D.C. on January 6.

But in the U.S. Senate, she worries Hogan would give Republicans too much power, a decisive vote against her interests.

PIER BLAKE: Gun violence.

There's education, housing, women's rights, health rights, and equality for everyone.

So there's a lot of things of Angela Alsobrooks' policies that I like.

LISA DESJARDINS: If you're unfamiliar with Angela Alsobrooks, you're not alone.

The executive of one of the state's largest counties, she had an impressive primary win, but, even so, one out of three Maryland voters still didn't recognize her name in a poll this month.

Alsobrooks is ahead in polls, but knows it's closer than Democrats like.

She stresses that voters here are attuned to control in Washington.

ANGELA ALSOBROOKS (D), Maryland Senatorial Candidate: It is close because there's a lot at stake here.

But I think Marylanders are very savvy, and they will understand the difference between a governor's race and a Senate race, one where our reproductive freedoms, democracy and so many other issues are on the ballot.

LISA DESJARDINS: As Alsobrooks and Democrats hope to prevent split-ticket voting in Maryland... MAN: Sherrod Brown wrote the All-American Flag Act.

LISA DESJARDINS: ... they need it in other states, like Ohio, where Senator Sherrod Brown is running on bipartisan patriotism and appeals to Republicans.

MAN: I'm a Republican have been my whole life.

I don't agree with Sherrod Brown on everything, but when it comes to fighting fentanyl, no one has done more than Sherrod Brown.

LISA DESJARDINS: Or in Montana, where this is an ad from Senator Jon Tester.

WOMAN: I'm a lifelong Republican.

MAN: I'm a lifelong Republican.

MAN: I'm going to vote for Donald Trump, but I'm voting for Jon Tester.

WOMAN: I'm voting for Jon Tester.

LISA DESJARDINS: In 2020, Trump won their states by eight and 16 points.

A common theme for Tester, Brown and Alsobrooks, running on abortion.

ANGELA ALSOBROOKS: I believe it's a woman's right to make our own health care decision.

LISA DESJARDINS: With Alsobrooks on the attack, Hogan began describing himself as pro-choice this year.

FMR.

GOV.

LARRY HOGAN: I ran for governor promising to protect abortion rights and I kept that promise for 10 years.

And now I have said I'm going to be a sponsor of the bill to codify Roe and I'm going to be a sponsor in IVF.

LISA DESJARDINS: Had you used the phrase pro-choice publicly as a politician before?

FMR.

GOV.

LARRY HOGAN: No, because I said I had my own personal feelings about it, but I was going to always never get between a woman and her doctor to make her own decision.

LISA DESJARDINS: But Maryland Democrats point out he vetoed a bill to expand access.

It would have let nurse practitioners and some others perform abortions.

When the legislature overrode the veto, he held back funding for training.

It's part of current voter thought.

While Colin supports Hogan's approach, it's a deal-breaker for Pier, a split in views in one of the states where voters who split their tickets, or don't, will determine the shape of Washington next year.

For the "PBS News Hour," I'm Lisa Desjardins in Annapolis, Maryland.