The present State of Israel was created on lands that had been, up to the end of WWII, in "Arab" control. As socialist tend to come from the disenfranchised segment of a society (didn't inherit, say 500 million $), they often side with the underdog.
Of course, those Arabs were generally avoided by the Arab League and put in refugee camps for what is now three generations, and called Palestinians. The fact that the Gaza Strip and West Bank are populated by mutually hated groups shows you what one general term can hide.
And if you are not in support of the State of Israel, to most people that is not being "anti-semetic" although there are some Jews who feel otherwise. The Congresswoman was making tis point, and suggesting that the tail iss wagging the dog perhaps.
I personally would love to relocate the United nations to Jerusalem but that is just me.