Hayden Padgett, chairman of the Young Republicans, praised Trump and his 39-year-old running mate, Sen. J.D. Vance, as a strong ticket for young people. Under Trump's first term, Padgett said, a bright future was promised.

"That future is diminishing as quickly as Biden's cognitive ability," he claimed, adding that young Americans are crippled under rising costs of education, groceries and housing.

"Our founders did not promise us happiness but the right to pursue it. And the Biden-Harris administration took that all away from us," he said.

Tennessee Gov. Bill Lee, the president of the National Governors Association, touched on Republican talking points -- from inflation to the border to parental rights -- while speaking on behalf of Republican governors.

"In the storm stirred by Washington, Republican governors across this country have stood as anchors of courage, their states as harbors of hope and their people as models of freedom," he said. "Governors can only do so much. We need strong leadership in the White House. We know what that looks like. We had it before, we need it again."

He said Republican governors are "joining together, unifying in support for Donald Trump for president."

J.D. Vance spoke with Vice President Kamala Harris on Tuesday afternoon, multiple sources familiar with the conversation told ABC News.

It was their first conversation since Vance was announced as Trump's running mate.

The conversation was "brief and respectful," according to a source with knowledge of the call.

Vance and Harris said they are looking forward to debating each other, the sources said, but no specifics were discussed.

-ABC News' Gabriella Abdul-Hakim, Hannah Demissie and Rachel Scott

The Republican National Convention's second night has begun, and the theme is "Make America Safe Again."

Several speakers -- including former U.N. ambassador Nikki Haley and Florida Gov. Ron DeSantis -- are expected to take the stage.