Allegheny County Controller Chelsa Wagner may be in a running dispute with police in Detroit, where she was detained last week, but she appears to have little to fear at home.

While nominating petitions were due for candidates seeking a spot on the May 21 primary ballot Tuesday, no one filed to challenge her on either the Republican or Democratic ballot.

The filing of petitions, which were due at 5 p.m., revealed only a few changes, especially in marquee races. Also uncontested on both the Republican and Democratic ballots is John Weinstein, the county treasurer. Rich Fitzgerald faces no Democratic opposition, and only Republican Matt Drozd, who formally announced his campaign last week, is seeking the post on the GOP side.

In the race for District Attorney, the only candidates remain incumbent Stephen Zappala and challenger Turahn Jenkins, both Democrats. No Republican filed in the race.

At the city level, Pittsburgh City Controller Michael Lamb appears to face no major-party opponent, though there have been a handful of changes in City Council races. Mark Brentley, who did not formally declare a campaign but has attended community forums, turned in petitions. He joins Chris Rosselot, Quincy Kofi Swatson, and Bobby Wilson in the bid to challenge incumbent Darlene Harris in City Council District 1.

In City Council District 3, South Side attorney Amy Schrempf’s withdrawal narrows the field of challengers for Bruce Kraus, but both Chris Kumanchik and Kenneth Wolfe filed petitions. In City Council District 9, the departure of challenger Leon Ford has opened up a space for Stanton Heights resident Stephen Braxton.

Braxton joins Cheryilie Fuller, Judith Ginyard, Randall Taylor, and Kierran Young in a crowded field to challenge incumbent Ricky Burgess.

District 5 incumbent Corey O’Connor looks poised to sail through the election cycle with no rival in either party. And in District 7, incumbent Deb Gross will face Deirdre Kane, who won the Democratic Committee’s endorsement on Sunday.

Three Pittsburgh school board races – all for open seats being vacated by incumbents -- may also be contentious. There are no fewer than four candidates challenging for school board District 2, which stretches along the southern bank of the Allegheny River: David Atkinson, Nosakhere Griffin-El, Devon Taliaferro, and Kirk Rys. The District 4 race – a hotly contested fight in the city’s East End – features Anna Batista, Pam Harbin, and Ashley Lynn Priore.

In District 6 of the South Hills, William Gallagher and Heather Fulton filed papers, pitting themselves against each other in a race where no obvious candidate had previously emerged.

School board candidates are permitted to cross-file as Republicans and Democrats, though only Rys did so in District 2, and both Batista and Harbin did in District 4. All the other candidates filed as Democrats alone.

There are a handful of match-ups for the part-time County Council as well. Perhaps the most notable is Bethany Hallam’s campaign against “at large” Democratic councilor John DeFazio, an inaugural member of the council. The Republican’s at-large councilor, Sam DeMarco, faces no challenger.

In County Council District 2, Democrats Michael Faddoul and Christine Allen will square off for the change to take on Cindy Kirk. Joseph Rudolph and incumbent John Palmiere will battle it out for the Democratic nomination in District 6, and Olivia Bennet will mount a progressive challenge to incumbent Denise Ranalli Russell in the Pittsburgh-centered District 13.

The ballot may change. Beginning Thursday, candidates will have the ability to review the validity of each other’s petitions, and potentially remove them in a court proceeding. And there may yet be write-in campaigns, especially in races where a party lacks a candidate.