Democratic senator calls for tighter oversight of Chinese firms with stocks that trade in the US

• Sen. Chris Van Hollen says Chinese companies are not playing fairly.
• The Maryland Democrat is pushing bipartisan legislation that increases oversight on more than $1 trillion worth of U.S.-traded Chinese companies.
• "They're the only country that is not playing by the rules," says Van Hollen, co-sponsor of the bill with GOP Sen. John Kennedy from Louisiana.

Sen. Chris Van Hollen is pushing bipartisan legislation that would require increased oversight of Chinese companies whose stocks trade in the United States and are collectively valued at more than $1 trillion.

The Maryland Democrat told CNBC on Thursday that, like all companies with shares on U.S. exchanges, Chinese firms should be held to the same U.S. standards of transparency and accountability.

"This is important to protect the integrity of U.S. exchanges and U.S. investors," said Van Hollen, co-sponsor with Republican Sen. John Kennedy from Louisiana of the Holding Foreign Companies Accountable Act.

Last week, senators including Republican Marco Rubio of Florida and Democrat Kirsten Gillibrand of New York introduced a similar bill. Gillibrand is one of the many candidates seeking her party's 2020 presidential nomination. Rubio unsuccessfully sought the GOP nomination for president in 2016.

"Why would we want to expose U.S. investors to the possibility of being defrauded by one country?" Van Hollen asked rhetorically on CNBC. China is the "only country that is not playing by the rules." The Van Hollen-Kennedy bill would give Chinese companies three years to come into compliance with U.S. standards.

In a letter Wednesday to U.S. Trade Representative Robert Lighthizer, Van Hollen and Kennedy asked that any U.S.-China trade deal include conditions requiring Chinese companies listed in the U.S. to comply with U.S. auditing and reporting requirements.

Van Hollen told "Squawk Box" on Thursday he has not heard back from Lighthizer.

The senator said he's trying to "elevate" this issue before President Donald Trump goes to the G-20 meeting at the end of the month in Japan, where he hopes to meet with Chinese President Xi Jinping.

Officials in the Trump administration have expressed optimism toward an agreement between Washington and Beijing, though many have said the G-20 meeting will only lay the groundwork for a potential deal.

"Eventually, this will end in negotiation," Commerce secretary Wilbur Ross told CNBC on Tuesday. "Even shooting wars end in negotiations."