By Liz Moyer

-- Stocks were weighed down by worries over China-U.S. relations on Tuesday amid House Speaker Nancy Pelosi's visit to Taiwan.

Also weighing on stocks: comments by various Federal Reserve officials that tossed some cold water on the notion that the Fed was close to backing off from its aggressive interest rate hikes.

Cleveland Fed President Loretta J. Mester said it would “take a while" to get inflation back to the Fed's 2% target and said an economic slowdown was necessary. San Francisco Fed President Mary Daly said the Fed’s job to bring inflation down was “far from done.” The Fed next meets in September.

Corporate earnings continued to pour in, with more set for Wednesday and later this week. In economic data, investors are waiting for the July jobs report on Friday, after job openings data on Tuesday fell short of expectations amid a cooling off in the labor market. Analysts expect Friday's jobs report to show the economy added 250,000 nonfarm jobs in July, which would be down from 372,000 the prior month.

Tesla Inc (NASDAQ:TSLA) shareholders meet Thursday to vote on the electric vehicle maker's 3-for-1 stock split.

Here are three things that could affect markets tomorrow:

1. CVS Health earnings

CVS Health Corp (NYSE:CVS) is expected to report earnings per share of $2.18 on revenue of $76.4 billion.

2. Moderna earnings

Moderna Inc (NASDAQ:MRNA) is expected to report earnings per share of $4.54 on revenue of $4.07 billion.

3. Services activity

The ISM non-manufacturing business activity reading for July is due out at 10:00 AM ET. Analysts expect it to say 54, which would be down from 56.1 the prior month.