Businesses and residents are being asked to put their weight behind calls for earlier trains from London.
In March First Great Western announced plans to start running earlier trains but wanted to gauge the response from the public and business before committing to a timetable change.
The company launched a consultation on the change that will introduce a new service leaving London at 7.06am and arriving in Plymouth at 10.37am.
At the moment the first train from London arrives in Plymouth at 11.17am so the new service would be 40 minutes earlier and have a 10-minute faster journey time.
Now the consultation is entering its final week and Plymouth City Council wants residents to help with the final push to get the service the city needs.
Council leader Tudor Evans said: "We have lobbied really hard for early morning trains and strongly support First Great Western's proposal.
"We have responded to the consultation to say we welcome and fully support the early train from London – it has been a long held aspiration for Plymouth, giving business the opportunity to do a day's work in the city.
"But what would make a really good impression for First Great Western, is a wave of words backing this idea in the last week of the consultation.
"We need to get the message out loud and clear that the people of Plymouth want this."
The West of England timetable consultation ends at 5pm on Friday 2 May.
The consultation with a summary of the proposals is available in electronic format.To respond in time to meet the deadline email email@example.com.