The deadline to get on the primary ballot for Republican and Democratic candidates is March 15. Any interested candidate will need to get 2,000 certified signatures by that date (which means well above 2,000 total if you figure in the names that will be thrown out), or they won’t be on the ballot.
The logistical requirements of actually meeting that hurdle are very high. This is not something that can be done by a political novice in two weeks – indeed it is a difficult task for established figures.
In the 2010 gubernatorial contest, both Democrats and Republicans were having a difficult time getting enough signatures, and most campaigns only managed to finish collecting them a few days before they were due. That was with a year (sometimes more) lead time. People now have two weeks.
Unless something changes – I have heard mention that the Maine legislature has the capability to push that date back, but my sources say there have been no conversations about that yet – that means that the only people that can pull it off are folks with already established political machines, or people with the money to instantly purchase the manpower to get it done.
This has implications for more than just the Senate race. If Chellie Pingree or Mike Michaud (or both) decide to run for the Senate seat, that means that potential candidates to replace them in the House of Representatives would have to meet that requirement as well