There is an unqualified right to the assistance of counsel at the sentencing hearing, as sentencing is a critical stage of the proceedings.[210]  A defendant may waive his or her right to the assistance of counsel at sentencing, but such a waiver must be knowing and voluntary under Faretta v. California.[211]  The defendant who seeks to proceed pro se must be fully informed of the ramifications of that decision,[212] including being advised of the “three elements” of self-representation.  S/he must be “‘made aware of (1) the nature of the charges against him [or her]; (2) the possible penalties; and (3) the dangers and disadvantages of self-representation.’”[213]  Any waiver of the right to counsel in the absence of such warnings renders the waiver unknowing and hence unconstitutional.

[210] Mempa v. Rhay, 389 U.S. 128 (1967). 

[211] Faretta v. California, 422 U.S. 806 (1975). 

[212] See id. at 835 (“Although a defendant need not himself have the skill and experience of a lawyer in order to competently and intelligently choose self-representation, he should be made aware of the dangers and disadvantages of self-representation, so that the record will establish that ‘he knows what he is doing and his choice is made with eyes open.’”).

[213] United States v. Hernandez, 203 F.3d 614, 624 (9th Cir. 2000).

POST CON RELIEF - GROUNDS - RIGHT TO COUNSEL - POTENTIAL SENTENCE SUFFICIENT FOR APPLICATION OF RIGHT TO COUNSEL
Alabama v. Shelton, 535 U.S. 654, 122 S.Ct. 1764, 152 L.Ed.2d 888 (2002) (suspended sentence that can potentially be transformed into actual incarceration is sufficient to trigger the Sixth Amendment right to counsel in misdemeanor cases).
NOTE: Misdemeanor convictions in which no sentence, or suspended sentence, to custody was imposed can still trigger immigration consequences. In these cases, the Sixth Amendment right to counsel does not apply, so post-conviction relief would not be possible on grounds of denial of counsel or ineffective assistance of counsel.

Tenth Circuit

POST CON RELIEF - SENTENCE - GROUNDS - INADEQUATE TIME FOR ARGUMENT
United States v. Algarate-Valencia, 550 F.3d 1238 (10th Cir. Dec. 30, 2008) (any error in failure to give defendant's attorney adequate time to speak at sentencing was not plain error affecting defendant's substantial rights).