WASHINGTON – Beginning in tweets telling four Democratic congresswomen of color to "go back" to their countries of origin, President Donald Trump's barrage of vitriol against the freshman lawmakers known as "the Squad" has dominated headlines.

Some political observers say it is part of a deliberate strategy to make the four women – who hail from their party's far-left wing and whose views critics say are out of the political mainstream – the face of the Democratic Party. Though many Americans have never heard of the four Democratic House members, a CBS News poll released this week shows that those who are familiar with them don't tend to view them favorably.

The poll, conducted from July 17-19 by YouGov, asked 2,099 adults about their views on Reps. Alexandria Ocasio-Cortez, D-N.Y.; Ilhan Omar, D-Minn.; Ayanna Pressley, D-Mass.; and Rashida Tlaib, D-Mich.

Ocasio-Cortez has the highest favorable rating at 23%, followed by Omar at 19%, Tlaib at 18% and Pressley at 17%.

Why are they called 'the Squad'?:How four freshman got their group nickname

'The Squad':These are the four congresswomen Trump told to 'go back' to other countries

Poll:President Trump's job approval rating reaches high mark after tweets

Racial rhetoric as distraction:Trump employs familiar tactic in attacks on 'Squad'

Ocasio-Cortez also has the highest unfavorable rating at 37%. Thirty-six percent have an unfavorable opinion of Omar, 34% say the same of Tlaib and 28% see Pressley unfavorably. The percentage of respondents who have a neutral view is the same for all four congresswomen at 19%.

A large share of the respondents say they had never heard of the women. Thirty-six percent did not know who Pressley is, 29% had not heard of Tlaib, 26% were unfamiliar with Omar and 21% did not know Ocasio-Cortez.

The poll has a margin of error of plus or minus 2.3%.

Tlaib:'I'm not going nowhere, not until I impeach' Trump

More:Trump calls congresswomen racist day after his adviser says the term is used to silence speech

Congressional leadership fares worse than the Squad.

Senate Majority Leader Mitch McConnell, R-Ky., is seen favorably by 16% of respondents, and 40% hold an unfavorable opinion of him. Twenty-six percent are neutral, and 18% say they had never heard of him.

Only 12% have a favorable view of House Minority Leader Kevin McCarthy, R-Calif., and 25% see him unfavorably. Twenty-eight percent are neutral, and 34% had never heard of him.

Twenty-three percent have a favorable view of House Speaker Nancy Pelosi, D-Calif., and 44% see her unfavorably. Twenty-four percent are neutral, and 9% had not heard of her.

Trump is seen favorably by 36% of respondents, unfavorably by 51% and neutrally by 11%. Two percent say they had never heard of him. Forty-six percent say he is doing a good job as president, and 54% say he is doing a bad job.

The poll, which was conducted after the president's tweets were condemned as racist in a House resolution, found that 87% of Americans say the country is divided along racial lines. A majority (53%) say Trump "tries to put the interests of whites over racial minorities," and 48% say the same of the Republican Party as a whole. Forty-one percent say the Democratic Party puts the "interests of racial minorities over whites."

Sixty-nine percent say they disagree with Trump's tweets telling the congresswomen – all of whom are American citizens and three of whom were born in the USA – to go back to their countries of origin and fix the problems there before trying to legislate change in the USA. Forty-eight percent say the tweets were racist and 34% say they were not. Fifty-five percent say they were unpresidential and the same percentage say they were unnecessary.

A USA TODAY/Ipsos poll last week found that 68% of Americans said Trump's tweets were offensive and 59% said they were un-American.

What does it mean for Democrats?:‘Send her back’ chant at Donald Trump’s rally moves race to center of 2020 contest

From 'Central Park Five' to 'the Squad':A dozen times Donald Trump has stoked racial tensions

'I love the tweet':Eric Trump says 95% of Americans agree with his dad's message to love USA or leave