Accepted Part Time Work, but same day, got offered a Full Time role at a different company

Hey there guys. I've been on somewhat of a journey through this past year, but this might be the most complicated one yet.

To recap, got laid off by my employer, march last year and have been job searching since. As my Visa term was about to end, I started getting a bit desperate. Eventually I got a part time role offer with an option for full time and visa sponsorship. The deadline to accept the offer was tomorrow. There were a few interviews/applications that I was awaiting the results for, but I had kinda given up, so thought let's give it a day buffer and accept the part time job. A few hours later, I got a mail from one of the companies I had interviewed for. A job offer for a full time role in my preferred field (IT).

Now what should I do? In the interview of the part time job, I had stated that if I were to get a visa sponsorship, I would like to work long term. However, this full time job offer is far more suited to my preferences. Issue is, I have accepted the part time job (nothing signed yet, just pressed accept on the form they mailed me). It should be noted that the joining date for the full time role is 1st of March. On my end, I'd be completely fine working part time until then. But how should I proceed with this? Any advice would be appreciated!

by skatlads15