CLINTON, Iowa - Pledging to invest in the "caring economy," Hillary Rodham Clinton proposed a new tax break Sunday for people caring for aging parents and grandparents.

The Democratic presidential candidate touted her latest proposal at a town-hall-style meeting in Iowa. She is seeking a tax credit to help offset up to $6,000 in caregiving costs for elderly family members. The credit would apply to 20 percent of those expenses for a maximum tax bill savings of $1,200.

"We need to recognize the value of the work that caregivers give to all of us, both those who are paid and the great number who are unpaid," Clinton said to the crowd of more than 400 people gathered at a middle school.

The caregiver proposal is part of a series of tax proposals geared at the middle class that Clinton is rolling out. In her plan, Clinton states that the number of Americans needing long-term care is expected to grow from about 12 million today to 27 million by 2050. She says that family members often have to take time away from work, using vacation time or personal time to provide care.

In other news:

Donald Trump says he saw people cheering the Sept. 11 attacks across the river in New Jersey - a claim officials strongly deny.

Trump first told the story Saturday at a rally in Birmingham, Ala., as he pressed the need for greater surveillance, including monitoring certain mosques, in the wake of the Paris attacks. "I watched when the World Trade Center came tumbling down. And I watched in Jersey City, New Jersey, where thousands and thousands of people were cheering as that building was coming down. Thousands of people were cheering," Trump said at the Birmingham rally.

He repeated the assertion Sunday in an interview with George Stephanopoulos on ABC's This Week, as Stephanopoulos said police had refuted any such rumors at the time.

"It did happen. I saw it," said Trump. "It was on television. I saw it."

In a statement, Jersey City Mayor Fulop said: "Trump is plain wrong, and he is shamefully politicizing an emotionally charged issue."

Footage of Muslims in Middle Eastern countries cheering news of the attacks were broadcast often on television, but there is no evidence in news archives of mass celebrations by Muslims in Jersey City.

Ben Carson likens his learning foreign policy to his ability to absorb changing complex medical practices. But he is standing by his support for monitoring groups he describes as "anti-American" and keeping Syrian refugees out of the United States.

Carson is among the leaders in national, and early-voting-state Republican polls. And yet, some have criticized the retired neurosurgeon as having insufficient grasp of foreign policy.

At a meeting of about 400 eastern Iowa GOP activists Sunday, he said: "They say 'Carson doesn't know anything about foreign affairs.' " He pointed to the continuing medical education all physicians are required to obtain as a sign of his capacity to learn, and said he would seek help from advisers.

"It doesn't matter, because what is really needed is a clear understanding of what the problems are and the ability to work with very talented people that we have," he said. "The world is changing very quickly. We have to be willing to continually update our knowledge and adjust to the things that are going on in our country."

At the request of the Associated Press, eight climate and biological scientists graded for scientific accuracy what a dozen top candidates said in debates, interviews, and tweets on climate science, using a 0 to 100 scale.

Clinton had the highest average score at 94. Three scientists did not assign Martin O'Malley a score, saying his statements mostly were about policy, which they could not grade. Two used similar reasoning to skip grading Gov. Christie and one did the same for Carly Fiorina. Ted Cruz of Texas had the lowest score, an average of 6. All eight put Cruz at the bottom of the class.

Bernie Sanders, with an 87, had the lowest score among the Democrats, dinged for an exaggeration when he said global warming could make Earth uninhabitable. Jeb Bush scored the highest among Republicans, 64, but one grader gave him a perfect 100. Bush was the only Republican candidate who got a passing grade on climate in the exercise.

Below Clinton's 94 were O'Malley with 91; Sanders, 87; Bush, 64; Christie, 54; John Kasich, 47; Rand Paul, 38; Fiorina, 28; Florida Sen. Marco Rubio, 21; Trump, 15; Carson, 13; and Cruz with 6.