SAN FRANCISCO, July 15 (Xinhua) -- Republican Senator Lisa Murkowski from Alaska state on Monday criticized U.S. President Donald Trump for making racially charged comments about four new Congresswomen who were outspoken opponents of Trump's immigration policy.

"There is no excuse for the president's spiteful comments -- they were absolutely unacceptable and this needs to stop," Murkowski said in a Facebook post in response to Trump's tweets on Sunday asking several Democratic Congresswomen to go back to their home countries rather than telling the U.S. people how to run the government.

Trump did not explicitly name the four Congresswomen, Alexandria Ocasio-Cortez, Ilhan Omar, Rashida Tlaib and Ayanna Pressley, but the references and context appeared to have an obvious link.

Among the leading Latino, black, and Arab Democratic lawmakers, who are all American citizens, only Omar was born in Somalia and came to the United States as a teenager in 1992. They have in recent months slammed Trump's immigration policy at the southern border.

"Why don't they go back and help fix the totally broken and crime-infested places from which they came," Trump said in a series of tweets on Sunday.

Murkowski urged Trump to stop making "personal vindictive insults" at the Democratic lawmakers.

"We have enough challenges addressing the humanitarian crises both at our borders and around the world. Instead of digging deeper into the mud with personal, vindictive insults -- we must demand a higher standard of decorum and decency," she said.