The MTA’s invitation for a farewell bash celebrating former chief Joe Lhota may have violated rules forbidding state agencies from campaigning, good-government advocates warned yesterday.

The e-mail invite sent to MTA staffers reads, “Come November, he could be elected New York City’s next mayor. But we remember him best as the Chairman who led us through Sandy.”

“This is using government resources to inadvertently and inappropriately promote his campaign,” said Dick Dadey, head of the group Citizens Union.

An MTA spokesman said: “Nothing in this invitation implies any endorsement or encouragement of his campaign.”