Whether a habeas petitioner must show that absent the attorney's deficient performance, no other evidence supported the verdict

QUESTION PRESENTED In order to obtain federal habeas relief for a violation of the Sixth Amendment right to the effective assistance of counsel, Strickland v. Washington, 466 U.S. 668 (1984), requires the habeas petitioner demonstrate (1) that counsel performed deficiently and (2) that the deficient performance resulted in prejudice. Where deficient performance is shown, must a habeas petitioner also show that absent the error, no other evidence supported the verdict? i