dialogue - Why does Indiana Jones say 'I like Ike'?

In Indiana Jones and the Kingdom of the Crystal Skull, short while after the beginning of the movie, Irina Spalko captured Indy and force him to lead the U.S soldiers military base which contains bunch of crates. Then, they've opened a highly magnetic crate which contains a weird creature. Meanwhile, Indy attempts to escape, however the attempts failed because Mac was pointing the gun at Indy's head and then reveals he's a spy working for Soviets. In that time, Indy and Mac had a conversation and then finally Spalko asked, 'No defiant last words, Dr. Jones?' to Indy. He replied as, 'I like Ike'.

Here is the script of the movie,

          INDY
Drop the guns, or Colonel 
Dr. Spalko is dead.

MAC TURNS HIS GUN ON INDY

          INDY 
Why, Mac?

          MAC
Well, what can I say, Jonesey?
I'm a capitalist, and they pay.

          INDY
After all those years we spent 
spying on the Reds? I thought 
we were friends, Mac.

          MAC
I've had a run of bad luck with 
the cards lately, mate. Awful. 
Bloody awful. I can't go home 
empty-handed again.

          SPALKO
No defiant last words, Dr. Jones?

          INDY
I like lke.

What does 'I like Ike' mean in this particular context?

Why does Indy say like that?