Is 'poll watching' illegal?

Poll watchers—whose purpose is to ensure that their party or cause has a fair chance at winning an election—are generally legal, although qualifications vary by state.

In most states, poll watchers are appointed by political parties or campaigns to monitor election administrators, track their party's voter turnout and report issues to party or polling-place officials. In some states, watchers must wear a badge; in others, they must be registered voters. In North Carolina, poll watchers are not allowed to speak to voters. In California, they may speak to voters, but not about election-related issues. In some states, poll watchers can challenge a voter's eligibility but are otherwise not supposed to interfere in the electoral process.

The Trump campaign has assembled what it has claimed will be an "army" of 50,000-plus volunteers to poll watch in battleground states, Politico reported.