WINCHESTER, Kentucky (AP) - Senate Republican Leader Mitch McConnell lambasted a liberal group for criticising the Asian heritage of his wife, former Labour Secretary Elaine Chao, calling its Twitter messages "racial slurs" and "the ultimate outrage".
Mr McConnell forcefully defended Ms Chao, who was born in Taiwan and who moved to the United States as an 8-year-old with her family aboard a freight ship.
"They will not get away with attacking my wife in this campaign," Mr McConnell told about 100 home-state supporters at a Republican dinner in Winchester.
"This woman has the ear of (at) McConnellPress - she's his (hash)wife," the group Progress Kentucky tweeted on Feb 14. "May explain why your job moved to (hash)China!"
Progress Kentucky removed the offending comments from Twitter after Louisville public radio station WFPL-FM aired reports about them. The group issued two apologies over the past week for what they described as "inappropriate tweets sent by our organisation."
"Elaine Chao is just as much an American as any of the rest of them," Mr McConnell said. "In fact, she had to go through a lot more to become an American."
Mr McConnell's aides had already criticised the tweets.
"Secretary Chao and her family are shining examples of the American dream: salt-of-the-earth folks who escaped oppression, came here with nothing, joined our great melting pot, worked exceptionally hard to build a thriving business, and then dedicated so much of their lives to giving back," said Mr Jesse Benton, manager of Mr McConnell's re-election campaign.
"It is unconscionable that anyone would use blatant race-baiting for political gain." Progress Kentucky executive director Shawn Reilly released a statement posted on the group's website.
"Those tweets did not reflect our values, and we are committed to making sure nothing like that happens again."
He said the volunteer who posted the comments no longer is affiliated with the group.
Criticism of the group was not limited to Mr McConnell and his supporters. Numerous Democratic leaders, including actress Ashley Judd, who is considering a challenge to McConnell in next year's election, spoke up too.
"Whatever the intention, whatever the venue, whomever the person, attacks or comments on anyone's ethnicity are wrong and patently unacceptable," she wrote in a Twitter message last Sunday.
Kentucky Democratic Party Chairman Dan Logsdon said the comments were "deplorable" and "have absolutely no place" in Kentucky politics.
Mr McConnell and his wife have faced similar slights in the past. In 2001, former state Democratic Party chairman Nikki Patton apologised for saying that Mr McConnell "passed up some good Kentucky pork to chow down at the Chinese money buffet".