The Learning and Skills Council would be wrong to impose the "nuclear option" of setting up the new centre, which would replace sixth-forms in schools in Carlisle and the surrounding area.
The Carlisle review comes after the LSC took over control of school sixth-form funding from local education authorities, and follows the announcement of plans to merge the county's four general FE colleges.
Eric Martlew, MP for Carlisle, is concerned that two of the schools are outside the area and the students they serve would struggle to get into town to study.
He says the existence of seven sixth forms provides choice. Even if staying-on rates were improved to acceptable levels, he argues, there would still be enough surplus places for students to change schools at sixth-form level.
He said: "What they have done is to use the nuclear option just to close all the sixth forms.
"If the schools don't like the LSC option they should come up with another one which allows youngsters the same opportunities as other parts of the country."
He and David Maclean, MP for neighbouring Penrith, both raised their concerns about the issue in the House of Commons last week.
The number of teenagers staying on at 16 is lower in Carlisle, at 74.4 per cent, than the rest of Cumbria and the national average, at 86.5 per cent.
The latest figures show 23 per cent of lower-sixth form students dropped out - compared with a national average of 13 per cent.
The proportion staying on after the first year of sixth form is also lower than in the rest of Cumbria or the average in the rest of England. Mick Farley, executive director of Cumbria LSC, said other options would be considered, including allowing the two outlying schools to retain sixth forms.
He said: "The consultation goes on until the end of the month."
If the LSC recommends going ahead with the sixth-form centre, there will be a further two-month consultation period for objections before a final decision is taken by the Education Secretary Charles Clarke.
The plans are supported by Carlisle college and one of the seven schools which would lose their sixth forms. The LSC believes a single centre in Carlisle would be large enough to offer a wider range of courses.