Marco uses a debate 1.01 level tactic, every time someone seeks to get him to renounce his stand by changing the subject, with an angry and frantic tirade, that you cannot do anything about immigration, until you control the border; and the more anyone presses him, as to what he will favor, once you control the border, the more frantically he shouts that you have to control the border, before you can decide on anything else.
I am not sure if Marco is regressing or just covering up bad intentions. His general performance a couple of days ago, was amateurish and inept. Trump treated him as a punk, and that is how he came across. Those who claim he did well, must have seen another debate than I saw; or are simply indulging their hostility to Trump.
Rubio is deluding himself, if he thinks his present tack will get him increased support. It will not. He needs to amend his tactics--and do it now;--or his whole political career is going to be the casualty.
Rubio is done. He will end up herding donkeys on a Texas ranch some where.