They seemed like Democratic activists. They were conservative spies.

Large donations to the Democratic National Committee — $10,000 each — had bought Beau Maier and Sofia LaRocca tickets to the debate. During a cocktail reception beforehand, they worked the room of party officials, rainbow donkey pins affixed to their lapels.

In fact, much about them was a lie. Mr. Maier and Ms. LaRocca were part of an undercover operation by conservatives to infiltrate progressive groups, political campaigns and the offices of Democratic as well as moderate Republican elected officials during the 2020 election cycle, according to interviews and documents.

Using large campaign donations and cover stories, the operatives aimed to gather dirt that could sabotage the reputations of people and organizations considered threats to a hard-right agenda advanced by President Donald J. Trump...

What the effort accomplished — and how much information Mr. Seddon’s operatives gathered — is unclear. Sometimes, their tactics were bumbling and amateurish. But the operation’s use of spycraft to manipulate the politics of several states over years greatly exceeds the tactics of more traditional political dirty tricks operations.