It’s impossible to approach the Democratic primary for Baltimore County executive without thinking about the last Democrat to win that job, the late Kevin Kamenetz. It’s not that we believe voters should consider which of the three major Democratic candidates in the race he would have supported — we have no idea who that would have been — but rather that they should focus on the evolution of Baltimore County that he, through his own evolving career, represented.

In the last 25 years, the region’s principal suburban jurisdiction has rapidly diversified. Its infrastructure has aged. Inequality of means and opportunity has spread. Old industries have died away. Homelessness and other social problems have proliferated. And the old equation in which leaders could count on constant development to fund the county’s needs is no longer working.

Kevin Kamenetz, first elected in the good old “b’hoys” days in Towson, recognized by the end of his career that sticking with the easy politics of the past was a recipe for a poorer future. Democrats need to pick another candidate this year who understands the new challenges Baltimore County faces and has the political courage to face them. Former Del. John A. Olszweski Jr. is the right candidate for Baltimore County’s future.

Mr. Olszewski was born into East Side Democratic machine politics — his father, the former county councilman John A. Olszewski Sr. was a last vestige of the labor union-Democratic club dominance in Dundalk — but he has become his own man. The first member of his family to go to college (in fact, he eventually earned a Ph.D. in public policy), he became a teacher and a member of the House of Delegates who not only backed labor-friendly causes but who would provide a crucial vote in support of marriage equality.

Mr. Olszewski presents himself as the most progressive candidate in the race, and his political development has become a major point of contention between his supporters and those of his opponents. Some of his votes in the legislature — particularly in opposition to gun control measures — have been closely scrutinized, and he now says his earlier stances on the issue were a mistake. Whether you take him at his word that his views have evolved, that issue is not one that the next county executive will have to grapple with to any great extent. On the issues that will matter for the county’s next leader, Mr. Olszewski stands far ahead of his rivals.

The most crucial of these is his support for Baltimore County’s housing discrimination settlement with the federal government. The best anyone else in the race can muster for it is grudging acceptance, which is a prime indication that they fail to understand what’s at stake. Unless Baltimore County takes affirmative steps to help integrate affordable housing throughout all its communities, it will develop the kinds of concentrated pockets of poverty that have plagued Baltimore City for decades, and it will reap all the attendant social problems that go with them. Supporting the settlement in its entirety — in fact, viewing it as merely a starting point — is a tough political stand in Baltimore County. But it’s the right one for the county’s future.

Mr. Olszewski recognizes the need for a more transparent and accessible county government — one that holds County Council work sessions in the evening and posts far more information about its workings online. He supports a voluntary system of public campaign financing, like the ones Montgomery and Howard counties have adopted (and the one Gov. Larry Hogan used to get elected four years ago), which would be the best tonic for a political system too easily dominated by moneyed special interests. And he has floated the idea of developer impact fees to help pay for the county’s growing needs.

Among his two rivals, County Councilwoman Vicki Almond most clearly represents politics as usual in Towson. No question, she has the most experience in county government. She says she knows what works and what doesn’t, but she hasn’t articulated much sense of what’s broken much less how to fix it. Her insistence, for example, that developers don’t wield outsize influence over county government is mind boggling.

The other major candidate in the race, state Sen. Jim Brochin, presents a tougher choice. We have supported him throughout his political career, and we have no doubt that he would shake things up in county government. He has never been part of the crowd in county politics but has instead practiced a kind of fierce independence throughout his four terms in the legislature. That suited his district — a sprawling and politically diverse swath of the central county — but we are concerned that it wouldn’t work as well in the role of county executive, in which he wouldn’t just be a deciding vote but would have to be the one to build coalitions in support of an agenda.

Mr. Olszewski, better known as Johnny O, represents a new generation of leadership and the hope of a brighter future for Baltimore County. In this race, he has shown himself to be a poised, thoughtful, articulate leader ready to provide a breath of fresh air in Towson. He has our endorsement.