Bosses of the Tnt network announced last month (Oct14) that the revived hit will not be coming back for a fourth season, prompting an online campaign by fans and stars of the show.
More than 500,000 viewers have since taken to Twitter.com to show their support for the sex-and-scandal drama to be given a reprieve or a move to another network, and Duffy has now told fans that this week (beg03Nov14) is crucial to the campaign in a 'now or never' post on the microblogging site.
He writes, "Coming week pivotal. We will be increasing our Pr. After that chances slimmer. SaveDallas."
Other Dallas stars backing the campaign include Linda Gray, Josh Henderson and Brenda Strong.