Story highlights Six in 10 American voters said they were mostly optimistic about Trump's presidency in November

But that number slipped to 52% in March and 43% today, according to Quinnipiac polling

Optimism has slipped more than 20 points -- from 74% in November to 51% now -- among whites without a college degree

Washington (CNN) More than six months into Donald Trump's young presidency, optimism among his core supporters -- and American voters at large -- is starting to fade.

After Trump's surprise victory in November, six in 10 American voters said they were mostly optimistic about his presidency. But that number slipped to 52% in March and 43% today -- now 10 percentage points underwater, according to new polling this week from Quinnipiac University.

Indeed, a majority of registered voters (53%) now say they are mostly pessimistic about the next few years of Trump's time in office.

And core groups that carried Trump to victory are not immune to the deteriorating optimism around the President about six months into his term.

Optimism for the Trump presidency among Republican voters dropped from a virtually unanimous 96% in January and March down to 84% now, with one in six Republicans now saying they are mainly pessimistic about his tenure.

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