President Donald Trump's approval rating is upside down in Indiana, according to a new poll.

Just 41 percent approve of the job Trump is doing as president, compared to 45 percent who disapprove, according to the results of the Old National Bank/Ball State University 2017 Hoosier Survey.

The negative approval rating suggests a significant decline in support for Trump since he won the home state of his vice president, Mike Pence, by a margin of 19 percentage points nearly a year ago.

“These survey results add to the evidence that the president’s approval has slipped a great deal since January,” said Chad Kinsella, a political science professor at the Bowen Center for Public Affairs, which conducts the annual survey.

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Other recent polling by Morning Consult showed Trump's net approval rating in Indiana fell from plus-22 percentage points in January to plus-5 in September.

”These results from October put his approval underwater in the state, with negative-5 approval," Kinsella said.

But Trump's support among his base remains strong, Kinsella said, with 77 percent approval among Republicans.

That's the group that Indiana Republican Party Chairman Kyle Hupfer focused on in a statement responding to the poll.

"Hoosier Republicans proudly support President Trump and Vice President Pence because of their unwavering commitment to reform our broken tax code and rid us of Obamacare’s stranglehold on our economy all while keeping America and Americans safe," he said.

But Indiana Democratic Party Chairman John Zody said the poll reflects growing discontent among Hoosiers.

“Our president likes to make big promises. So far, he hasn’t delivered,” he said. “These polling numbers reflect Hoosiers’ rapidly mounting frustration with the President’s failure to articulate a vision that lifts up working families and his inability to get anything done.”

The poll surveyed 600 adult Hoosiers. The margin of error was plus or minus 5.3 percentage points.

Call IndyStar reporter Tony Cook at (317) 444-6081. Follow him on Twitter and Facebook.