The Yankton Sioux Tribe appeals the district court’s1 denial of its motions for joinder and for dismissal of a motion to approve the proposed settlement in an action brought by a tribe member, Shirley Arrow, against Gambler’s Supply, Inc., pursuant to 25 U.S.C. § 81. We affirm.
I.
The Yankton Sioux Tribe and Gambler’s Supply signed a management agreement in 1990 for the operation of a casino on tribal lands. As the screening process required by 25 U.S.C. § 81 resulted in disapproval of the contract by the Bureau of Indian Affairs, the parties revised the management agreement and executed an interim agreement under which to conduct business pending BIA approval. The casino began operation on June 22, 1991. Four months later, the BIA sent a letter informing the Tribe that the amended *409management agreement could be approved once the requisite background investigation was finished. Before the approval process was complete, howéver, the Tribe resolved to terminate its relationship with Gambler’s Supply and withdrew the management agreement from consideration by the BIA. The Tribe subsequ ently agreed to pay Gambler’s Supply a settlement of $1,420,000.
On October 26, 1992, Arrow brought a qui 'tam action against Gambler’s Supply under 25 U.S.C. § 81, claiming that both the management agreement and the settlement were void for lack of BIA approval. She sought return of $1,912,455.08 that the gaming company had received from the casino operations and of the $1,420,000 settlement. One month prior to trial, the parties agreed to settle the case for $100,000, to be divided equally between Arrow and the Tribe as required by the statute, and an additional $26,500 in attorney fees. After learning of the proposed settlement, the Tribe filed a motion for join-der under Fed.R.Civ.P. 19 as well as a motion to dismiss the motion to' approve the settlement. The district court denied the motion for joinder on the basis of laches and approved the settlement between Arrow and Gambler’s Supply.
II.
A.
The Yankton Sioux Tribe claims that the district court erred in its dismissal of the Rule 19 motion for joinder in Arrow’s action against Gambler’s Supply. We note at the outset that only a party may make a Rule 19 motion, although, of course, a court may sua sponte join a party for good cause. See,, e.g., Fed.R.Civ.P. 21 (describing the procedure for joinder or dismissal of parties); Thompson v. Boggs, 33 F.3d 847, 858 n. 10 (7th Cir.1994) (noting the lack of any precedent granting a non-party’s motion for joinder). We think it proper, however, to treat the Tribe’s motion as a request to intervene pursuant to Fed.R.Civ.P. 24.
The issue of whether a movant is entitled to intervene as of right is a question of law that is ordinarily reviewed de novo. Mille Lacs Band of Chippewa Indians v. Minnesota, 989 F.2d 994, 998 (8th Cir.1993). In this case, the district court based its decision on the Tribe’s failure to act in a timely fashion, for which the appropriate standard of review is abuse of discretion. Id.; NAACP v. New York, 413 U.S. 345, 366, 93 S.Ct. 2591, 2603, 37 L.Ed.2d 648 (1973). Among the considerations that bear on the question of timeliness are how far the litigation had progressed at the time of the motion for intervention, the prospective intervenor’s prior knowledge of the pending action, the reason for the delay in seeking intervention, and the likelihood of prejudice to the parties in the action. Id. The Yankton Sioux Tribe monitored Arrow’s suit against Gambler’s Supply for nearly two years and then moved to join the litigation when the parties reached a settlement agreement one month before the trial date. Even if the Tribe’s proposed intervention would not have subjected the existing parties to the added expense of reopening settlement negotiations and preparing for trial, we cannot say that the district court improperly weighed the relevant considerations, and thus abused its discretion, in denying the motion.
B.
Although our holding that the Tribe’s motion was untimely is sufficient to dispose of this appeal, we nevertheless consider whether the district court would have been obliged to allow the Tribe to intervene if the motion had been timely. Rule 24(a)(2) requires allowing such intervention when the movant has an interest in the subject matter of the litigation that might be impaired 'by disposition of the litigation, unless that interest is “adequately represented by existing parties.” Although the Tribe concededly has an interest that could be impaired by disposition-of Arrow’s action against Gambler’s Supply, it still bears the burden of demonstrating that Arrow does not adequately protect its interest. Mille Lacs, 989 F.2d at 999. This burden is usually minimal but may be higher under certain circumstances. Id. For example, other circuits have held, we think correctly, that there is a presumption of adequate representation when the prospective intervenor’s interest is identical to that of an *410existing party. See Purnell v. City of Akron, 925 F.2d 941, 950 (6th Cir.1991); Bottoms v. Dresser Industries, 797 F.2d 869, 872 (10th Cir.1986). ■ In this case, Arrow is not only on the same side as the Tribe, but her interests are literally identical with the Tribe’s because 25 U.S.C. § 81 requires an equal distribution between them of any amount recovered. There is no evidence in the record, moreover, that Arrow failed to pursue the litigation vigorously. In fact, the Tribe admitted during the district court hearing on the motion that it had no objection to the manner in which Arrow prosecuted the suit. Although the Tribe now argues that Arrow’s representation was inadequate because her modest income made her willing to settle for less than the value of the suit, Congress expressly provided for qui tam actions without requiring participation by a tribe. We decline to undermine this statutory provision by predicating our evaluation of the representation upon Arrow’s degree of risk aversion or upon an attempt to determine the comparative utility accorded the monetary amount of the settlement by Arrow and the Tribe, especially when the record is wholly void of any information regarding Arrow’s wealth and income. Interpersonal utility comparisons are difficult to make at best. Therefore we believe that even a timely Rule 24(a) motion would not have entitled the Tribe to intervene as of right.
C.
Finally, we consider whether the district court abused its discretion by failing to allow permissive intervention by the Tribe. See McLean v. Arkansas, 663 F.2d 47, 48 (8th Cir.1981) (standard of review). Rule 24(b)(2) allows a court to. grant such intervention “when an applicant’s claim or defense and the main action have a question of law or fact in common” after determining whether “the intervention will unduly delay or prejudice the adjudication of the rights of the original parties.” The transcript of the district court hearing on the Tribe’s motion indicates that this issue received due consideration. We thus conclude that the district court properly exercised its discretion by denying the tribe’s motion.
III.
The Tribe further claims that the district court erred in dismissing its motion for dismissal of the motion made by Arrow and Gambler’s Supply to approve the proposed settlement. Because the tribe was not entitled to intervene in the action, it lacked standing to challenge the parties’ settlement. Thus the district court correctly dismissed the Tribe’s motion.
IV.'
For the foregoing reasons, we affirm the judgment of the district court.
. The Honorable John B. Jones, Senior District Judge for the District of South Dakota.