Antwoine Petty pleaded guilty in Missouri state court to several burglary-related charges and received a nine year sentence. Petty filed a state postconviction motion, which was denied as untimely because it was filed more than ninety days after Petty’s sentencing. In February 1996, Petty filed a pro se 28 U.S.C. § 2254 petition for writ of habeas corpus. The magistrate judge, to whose jurisdiction the parties consented under 28 U.S.C. § 636(c) (1994), denied habeas relief, concluding Petty had procedurally defaulted his claims and had not shown cause and prejudice excusing his default.
On appeal, Petty concedes he did not file a timely state postconviction motion. (Appellant’s Br. at 8.) Petty contends, however, that the magistrate judge committed error in concluding he did not show cause and prejudice to overcome his procedural default because:
[Petty] did not know (and could not have known) that the state trial court was going to renege on its promise to release him on probation [if he successfully completed a drug treatment program] until after he successfully completed [the] ... program — more than 90 days later_ By failing to take into account the effect of the time to complete the drug treatment program (more than 110 days) on Petty’s ability to know whether he had a basis to file a [state postconviction] motion, the district court erred in concluding that Petty’s failure to file such a motion within the 90 day time limit was inexcusable.
(Appellant’s Br. at 9-10.) In other words, Petty argues he believed the trial court would give him probation when he completed his drug treatment program and could not know he had a factual basis for *400filing a state postconvietion motion until after the trial court refused to release Mm — more than ninety days after sentencing. The Government contends Petty cannot raise this allegation of cause on appeal because Petty did not present it to the magistrate judge. We agree.
A liberal reading of Petty’s § 2254 petition and supplemental pleadings reveals that Petty presented five claims to the magistrate judge. See Prince v. Lockhart, 971 F.2d 118, 121 (8th Cir.1992) (pro se habeas petition entitled to liberal construction); Thompson v. Missouri Bd. of Parole, 929 F.2d 396, 399 (8th Cir.1991) (court will review pro se habeas petition and any supplemental pleadings to determine whether petitioner raised claim in district court). In his petition, Petty alleged: (1) ineffective assistance of counsel because his attorney did not discuss defense strategies with Petty but simply gave him the plea agreement; (2) the trial court engaged in judicial misconduct and breached the plea agreement by refusing to release Petty on probation as promised after receiving a release recommendation from the drug treatment facility; (3) Petty’s plea was involuntary because he pleaded guilty only after his counsel and the trial court promised to release Petty on probation if the treatment facility recommended release; and (4) Petty did not have access to legal materials or legal assistance during the first 110 days of his incarceration at the drug treatment facility, causing Petty to miss the ninety-day filing deadline for his state postconviction motion. In addition to the claims asserted in his petition, Petty vaguely asserted in his objections to the Government’s response to his petition that “[a]s the petitioner indicated in his Habeas Petition, he was prevented from [raising his first three grounds of relief in a state postconviction motion] d[ue] to Governmental Interference which is both cause and actual prejudice for his procedural default.”
Even read liberally, none of these allegations encompasses Petty’s new claim on appeal that he did not know of the factual basis for state postconviction relief until it was too late to file a motion. Because neither the magistrate judge nor the Government had notice of this particular claim, Petty has procedurally defaulted it. See Prince, 971 F.2d at 121. Petty has not attempted to show cause for his failure to raise this issue before the magistrate judge, and, thus, we cannot excuse his procedural default. See id.
We affirm the denial of Petty’s petition for writ of habeas corpus.