What is the test for establishing deficient performance of counsel?

We need not and do not determine whether Lopez established deficient performance because we conclude that even if counsel's performance was deficient, Lopez has failed to sustain his burden on the issue of prejudice. Where the ineffective assistance of counsel is alleged to have caused the defendant to reject a plea offer, "a defendant must show that but for the ineffective advice of counsel there is a reasonable probability that the plea offer would have been presented to the court (i.e., that the defendant would have accepted the plea and the prosecution would not have withdrawn it in light of intervening circumstances), that the court would have accepted its terms, and that the conviction or sentence, or both, under the offer's terms would have been less severe than under the judgment and sentence that in fact were imposed." (Lafler v. Cooper (2012) 566 U.S. 156, 164.)