Democratic presidential nominee Hillary Clinton and her vice-presidential running mate, Sen. Tim Kaine (D-Va.), will release new tax returns in the coming days, according to a person close to Clinton.

It is the campaign's latest effort to pressure Republican nominee Donald Trump into releasing his returns. Trump has said that he will not release his tax returns because they are being audited.

Clinton has released tax returns every year dating to 1997. This newest return will include her taxes from 2015.

The release this week will also include Kaine and his wife, Anne Holton, who will provide returns from the past 10 years, according to the person familiar with the plan, who was not authorized to speak publicly ahead of the release.

They will include information such as Clinton's and Kaine's income, charitable giving and tax rate for the year.

Clinton and her allies have stepped up pressure on Trump to release his taxes. Recently, at a campaign event in Omaha, billionaire Warren Buffett challenged Trump to release his taxes, saying that he would meet Trump "anytime" and "anywhere" to compare their returns.