Sen. Marco RubioMarco Antonio RubioSenate passes legislation supporting Hong Kong protesters Senators voice support for Iran protesters but stop short of taking action McConnell urges Trump to voice support for Hong Kong protesters MORE (R-Fla.) is unlikely to tune into the first Democratic presidential debate, which he says will be a contest for candidates to show "who is the most liberal." 

"I think it's a race to the left. All the candidates will see which one can out-liberal the other," the Republican presidential candidate said in a Fox News interview Monday night.
 
ADVERTISEMENT
 
"In essence, they want to do everything Barack Obama is doing, but even more of it. They want to expand the Obama agenda," Rubio said.
 
Rubio has become the target of attacks from rivals Donald Trump and Jeb Bush after seeing his stock rise following the first two GOP debates in August and September. 
 
The freshman senator is likely to be a target of Democratic candidates, too, when they take to the stage Tuesday night in Las Vegas.
 
"I doubt I'll be watching. I've got a busy day ahead of me. I'm sure I'll see the clips and the highlights," Rubio said.