Last-minute challenges in battleground Pennsylvania target thousands of mail-in ballots

Thousands of mail-in ballots in the battleground state of Pennsylvania have been targeted for rejection as part of a last-minute campaign that has set off alarms for voting rights groups and exasperated local election officials.

​ Thousands of mail-in ballots in the battleground state of Pennsylvania have been targeted for rejection as part of a last-minute campaign that has set off alarms for voting rights groups and exasperated local election officials. Read More Breaking News, Latest News and Videos | CNN