Mackenzie leading the Republican race for Pennsylvania's 7th

Pennsylvania is already in the thick of campaign season for November's presidential and U.S. Senate races, but Democrats and Republicans in the Keystone State still need to choose their candidates in a slate of other consequential races down the ballot this fall. It'll all go down in the state's April 23 primaries. Among the key races to watch: a couple of incumbent House members — one progressive Democrat and one moderate Republican — are fighting off challengers from their right, and the parties will choose their candidates in two other...