"Sponsorship" is not a legal term but like an H-1B, it requires a job offer so it is not just an individual filing. Broadly, there are two ways to get a TN, one by applying with U.S. Customs and Border Protection with a letter from an employer and the other is for that employer to file a TN petition with USCIS. When the latter approach is taken, the employer must complete, sign, and submit forms as the petitioning (read, "sponsoring") employer and these forms are many of the same forms that an H-1B petitioning employer must submit. So, "sponsorship" by an employer is required for those seeking to work in TN status.
"Sponsorship" is not a legal term but like an H-1B, it requires a job offer so it is not just an individual filing. Broadly, there are two ways to get a TN, one by applying with U.S. Customs and Border Protection with a letter from an employer and the other is for that employer to file a TN petition with USCIS. When the latter approach is taken, the employer must complete, sign, and submit forms as the petitioning (read, "sponsoring") employer and these forms are many of the same forms that an H-1B petitioning employer must submit. So, "sponsorship" by an employer is required for those seeking to work in TN status.