Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 110
Troubleshooting
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
General Maintenance Action; General Flight Cancelled / Delayed
Aircraft
During boarding First Officer and I smelled an acrid odor.  It started to get stronger and the flight attendants called and let us know they smelled it as well.  Since the odor was getting stronger and we didn't have any immediate indication as to what was causing it; I chose to expeditiously deplane the aircraft through the main cabin door.  While exiting the aircraft; one of the customers remarked that he thought the smell 'was electrical in nature.'  After deplaning we called Maintenance out to look at the jet.  After some back and forth about possible causes; Maintenance decided to take the jet out of service to do a deeper dive.  We swapped aircraft and completed the flight with a different tail number.
Air Carrier Captain reported a fume event during boarding. Maintenance removed the aircraft from service and another was assigned.