In a general election matchup, 49% of likely voters would pick Jackson and 46% would choose Collins, according to the poll from the University of New Hampshire Survey Center.
Two of Jackson's top rivals dropped out of the race Sunday, at the same time as his campaign claimed to have secured the support of at least 400 delegates to the Democratic party's U.S. Senate nominating convention.
Two of the top candidates for Senate announced Sunday they will withdraw from the Democratic party's process for selecting a replacement for Graham Platner.
Thursday's debate hosted by News Center Maine comes a little over a week before Democrats will hold a convention to pick a new nominee to take on Sen. Susan Collins.
The U.S. Senate candidate announced Wednesday that he was exiting the race. Now, the party must choose a replacement to face Sen. Susan Collins in November.
A suit filed by a signature gatherer and three people who signed petitions is specifically focused on 1,520 signatures that they say should not have been invalidated.