An intravascular catheter has a telescope section including telescoped inner and outer tubular catheter members, a sheath having a proximal end anchored to an end of one of the inner and outer catheter members, and an elongated flexible drive member coaxially disposed within and being proximally and distally movable through the sheath. The drive member has a distal portion received in the sheath, and a second, unsheathed portion extending beyond the sheath into the interior of the telescope section. the unsheathed portion of the drive member has a stiffness greater than that of the sheath-disposed distal portion of the drive member and of a sufficient magnitude such that the unsheathed portion of the drive member is self-supporting within the telescope section.
