(CNN) During the longest government shutdown in US history, President Donald Trump has been losing support among those who may be his strongest supporters -- white Americans who don't have college degrees.

Among this group, only 45% said they approved of the job Trump is doing as President, according to a recent CNN poll conducted by SSRS. That is the lowest level of support among this subgroup by 1 percentage point in CNN's surveys and a dip from a poll conducted in early December, before the partial shutdown, when 54% of whites without college degrees approved of his job as President and 39% disapproved.

The dip is notable since among whites who hold college degrees, Trump's ratings are largely unchanged in the last month and remain sharply negative -- 64% disapprove and 32% approve.

This trend is backed up by a new Quinnipiac poll released Tuesday. Approval for the President remained somewhat stable between its mid-December poll and now among whites without college degrees (down from 56% to 53%), but disapproval increased from 37% to 43%. That is going from a net 19% positive approval to a net 10% for Trump, a 9-point loss.

The January CNN poll f ound a majority of Americans placed most of the blame for the government shutdown on Trump (55%) over the Democrats in Congress (32%). Trump has tried to push back from his December claim that he would be proud to shut the government down.

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