SUMMARY ORDER
Plaintiff-Appellant Larry Porter, pro se, appeals from the district court’s judgment (1) granting summary judgment for the defendants in Porter’s action brought pursuant to 42 U.S.C. § 1988, and (2) denying his motion for reconsideration. We assume the parties’ familiarity with the underlying facts, the procedural history of the case, and the issues on appeal.
We review de novo an order granting summary judgment. See Miller v. Wolpoff & Abramson, L.L.P., 321 F.3d 292, 300 (2d Cir.2003). Under Rule 56(a) of the Federal Rules of Civil Procedure, a district court “shall grant” summary judgment if the evidence shows “that there is no genuine dispute as to any material fact.” Accord Celotex Corp. v. Catrett, 477 U.S. 317, 322-23, 106 S.Ct. 2548, 91 L.Ed.2d 265 (1986). A dispute is “material” only if it “affeet[s] the outcome of the suit under the governing law.” Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 248, 106 S.Ct. 2505, 91 L.Ed.2d 202 (1986). In assessing a motion for summary judgment, we are “required to resolve all ambiguities and draw all permissible factual inferences in favor of the party against whom summary judgment is sought.” Terry v. Ashcroft, 336 F.3d 128, 137 (2d Cir.2003) (internal quotation marks omitted). However, “conclusory statements or mere allegations [are] not sufficient to defeat a summary judgment motion.” Davis v. New York, 316 F.3d 93, 100 (2d Cir.2002).
The district court properly granted the defendants’ summary judgment motion with respect to Porter’s claims against Commissioner Glenn Goord, Special Housing Unit Director Donald Selsky, Superintendent Michael McGinnis, Captain James Waite, Lieutenant Richard Strong, Senior Investigator Thomas Todd, Lieutenant Richard Donahue, and Nurse Connie DeMeritt. Porter failed to offer evidence suggesting that these defendants were personally involved in the alleged violation of Porter’s constitutional rights. See Colon v. Coughlin, 58 F.3d 865, 873 (2d Cir. 1995).
*23 The district court also correctly granted summary judgment in favor of the defendants with respect, to the Eighth Amendment claim stemming from the alleged delay in medical treatment, because Porter offered no evidence that this delay was the result of anyone’s deliberate indifference to his medical needs. See Chance v. Armstrong, 143 F.3d 698, 702 (2d Cir. 1998).
As to the excessive-force claim, the defendants concede that the district court erred in granting summary judgment for New York State Department of Correctional Services (“DOCS”) Officers Paul Weed, Peter Mastrantonio, and Joel Armstrong. Porter has disputed the defendants’ account of the incident, specifically denying that he provoked Officer Mastrantonio by kicking, him and that he violently resisted the subsequent attempts to subdue him. Moreover, the record does not indicate whether the evidence adduced by Porter disputing the officers’ account is “contradict[ed]” by the surveillance video that supposedly captured (a portion of) the incident. See Scott v. Harris, 550 U.S. 372, 378, 127 S.Ct. 1769, 167 L.Ed.2d 686 (2007) (holding that a party cannot defeat summary judgment by adducing testimony contradicted by a videotape of the incident).
The defendants also concede that the district court erred in granting sum-, mary judgment for Sergeant Gary Morse on Porter’s claim that Morse failed to intervene to prevent the other officers from using excessive force. “A law enforcement officer has an affirmative duty to intercede on the behalf of a citizen whose constitutional rights are being violated in his presence by other officers,” O’Neill v. Krzeminski, 839 F.2d 9, 11 (2d Cir.1988), and “is hable for the preventable harm caused by the actions of the other officers where that officer observes or has reason to know ... that excessive force is being used.” Anderson v. Branen, 17 F.3d 552, 557 (2d Cir.1994). The record reflects a genuine issue of material fact as to whether Morse failed to protect Porter from an alleged assault by officers that he knew or had reason to know was occurring.
To the extent that Porter has challenged the denial of his requests for injunctive relief, the district court did not abuse its discretion in denying those requests for the reasons stated in its decision. See Carlos v. Santos, 123 F.3d 61, 67 (2d Cir.1997) (explaining that “[w]e review a denial of a request for a permanent injunction for abuse of discretion.”).
Porter has abandoned any challenge to the dismissal of his remaining claims — including his First Amendment retaliation claim — by failing to sufficiently raise such a challenge in his brief. See LoSacco v. City of Middletown, 71 F.3d 88, 93 (2d Cir.1995). Porter has also abandoned any challenge to the denial of his reconsideration motion.
We have considered Porter’s other arguments on appeal and have found them to be without merit. Accordingly, the judgment of the district court is hereby AFFIRMED, in part, and VACATED, in part. The case is REMANDED to the district court for further proceedings and with instruction to appoint counsel for Plaintiff-Appellant Porter.