Power of Attorney

     Know all by these presents, that the undersigned hereby constitutes
and appoints each of Martin A. Naegelin, Jr. and Derrek Weaver, signing
singly, the undersigned's true and lawful attorney-in-fact to:

(1) execute for and on behalf of the undersigned, in the undersigned's
    capacity as an officer and/or director of Rush Enterprises, Inc. (the
    "Company"), Forms 3, 4 and 5 in accordance with Section 16(a)
    of the Securities Exchange Act of 1934 and the rules thereunder;

(2) do and perform any and all acts for and on behalf of the undersigned
    which may be necessary or desirable to complete and execute any such
    Form 3, 4 or 5, complete and execute any amendment or amendments
    thereto, and timely file such form with the United States Securities
    and Exchange Commission and any stock exchange or similar authority;
    and

(3) take any other action of any type whatsoever in connection with the
    foregoing which, in the opinion of such attorney-in-fact, may be of
    benefit to, in the best interest of, or legally required by, the
    undersigned, it being understood that the documents executed by
    such attorney-in-fact on behalf of the undersigned pursuant to this
    Power of Attorney shall be in such form and shall contain such terms
    and conditions as such attorney-in-fact may approve in such
    attorney-in-fact's discretion.

     The undersigned hereby grants to each such attorney-in-fact full
power and authority to do and perform any and every act and thing
whatsoever requisite, necessary, or proper to be done in the exercise
of any of the rights and powers herein granted, as fully to all intents
and purposes as the undersigned might or could do if personally present,
with full power of substitution or revocation, hereby ratifying and
confirming all that such attorney-in-fact, or such attorney-in-fact's
substitute or substitutes, shall lawfully do or cause to be done by
virtue of this Power of Attorney and the rights and powers herein
granted. The undersigned acknowledges that the foregoing
attorneys-in-fact, in serving in such capacity at the request of the
undersigned, are not assuming, nor is the Company assuming, any of
the undersigned's responsibilities to comply with Section 16 of the
Securities Exchange Act of 1934.

     This Power of Attorney shall remain in full force and effect
until the undersigned is no longer required to file Forms 3, 4 and 5
with respect to the undersigned's holdings of and transactions in
securities issued by the Company, unless earlier revoked by the
undersigned in a signed writing delivered to the foregoing
attorneys-in-fact.

     IN WITNESS WHEREOF, the undersigned has caused this Power of
Attorney to be executed as of this 1st day of April 2007.

     /S/ STEVEN L. KELLER

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