On a myriad of issues, she linked Katko's positions to his acceptance of donations from various industries. On health care, she said Katko and the GOP are aligned with the insurance companies and pharmaceutical lobbyists.

"This is a time for moral courage," she said. "We need leaders who do what's right, not what's easy."

Onondaga County Republican Chairman Tom Dadey welcomed Balter and other Democrats to the race Tuesday.

"We are more excited than ever to kick off a robust discussion on the issues and our future," he said. "Until then, Congressman John Katko is focused on delivering for central New York."

Democrats have named Katko as a top target in 2020. The Democratic Congressional Campaign Committee, the House Democrats' campaign arm, has listed the race as a priority. The group also added Katko to a "retirement watch list," although the Republican congressman has said he intends to run next year.

Katko raised more than $284,000 in the first quarter of the 2020 election cycle — an indication he is seeking re-election. He also submitted a statement of candidacy to the Federal Election Commission.