For-profit colleges have increased their lobbying against proposed Education Department rules to cut off federal financial aid to programs whose students take on too much debt for training that provides little likelihood of leading to a well-paying job.

In addition to making personal visits to Capitol Hill, executives at the colleges have provided employees with “personalized” letters to send to Washington and urged students to speak out against the proposals.

So far, the department has received about 45,000 letters on the proposed “gainful employment” regulations, in the comment period that ends Thursday.

Last week, John Sperling, the founder of the nation’s largest for-profit college, the University of Phoenix, e-mailed every member of Congress, seeking help opposing the regulations, and attached a sample letter to be sent to Education Secretary Arne Duncan, asking him to withdraw them.