renege on (something)
To withdraw from or fail to do or carry out something, such as a given commitment, promise, plan, or situation. People are beginning to worry that the president is going to renege on his campaign promises. The merger was all set to move forward, but the other company reneged on the agreement at the last possible moment.
renege on something
to go back on one's promise or commitment. I am mad at you because you reneged on your promise! I did not renege on what I promised.
renege on
v. To fail to carry out some promise or commitment; go back on a promise or commitment: If I had known that you would renege on your contract, I never would have hired you.