Virginia senator Tim Kaine avoided addressing Hillary Clinton's use of a private email server as secretary of state Tuesday during the vice-presidential debate, after being asked whether the scandals surrounding Clinton are fueling lack of trust among voters.

Kaine discussed Clinton's "passion" for "serving others," recalling her time as a lawyer for the Children's Defense Fund and her political tenure, but did not turn to the email scandal or potential conflicts of interest linked to the Clinton Foundation, despite being asked about both.

The Virginia senator then contrasted Clinton's character to that of Donald Trump, describing the businessman as "insult-driven" and "selfish."

"Donald Trump always puts himself first," he said.

A Washington Post/ABC News poll conducted before the first presidential debate found that 62 percent of voters would not describe the former secretary of state as "honest and trustworthy."