Sounds like the person is very much behind Donald Trump. Lightweight choker -- lightweight refers to the sport of boxing which has various classes of competition according to the weight of the fighter. Calling Rubio a lightweight means he is outclassed by the heavyweight competition. The writer was probably insulting Rubio's intelligence or ability. Choker is another sports analogy, it refers to a team or a player that cannot seem to make big plays or score runs when there is a lot of pressure to perform - like in a championship game. They get nervous and 'choke', they do poorly. Probably referring to Rubio's performance in the last debate when Christie gave him such a hard time. Politics! It is the same in every language and country I am sure - crazy!

I had to look this one up when I read it this morning, myself: https://www.washingtonpost.com/news/post-politics/wp/2015/11/10/donald-trump-creates-a-new-nickname-for-marco-rubio-lightweight-choker/ It's a neologism / Trumpism. I wouldn't expect to ever hear it again.