TN visa is a non-immigrant visa. The submission of PERM does not mean that the immigration process begins. Therefore, the employer submits PERM to U.S. Department of Labor, and the applicant can extend the TN visa. When the employer submits the I-140 to USCIS for the applicant, the applicant has a migration tendency, but the approval of I-140 does not mean that TN holders can no longer apply for TN visas.
(For more information, please contact firstname.lastname@example.org)