Wall Street's main indexes were set to open flat on Tuesday as investors stayed away from making big bets ahead of a Senate vote on a much-anticipated infrastructure bill.

After the vote on passage of the $1 trillion bipartisan infrastructure bill at 11 a.m. ET (1500 GMT), the Senate would immediately begin to debate $3.5 trillion in additional investments to jump-start road and bridge-building projects over the next five years and new social programs over the next decade. 

With new coronavirus cases rising steadily in the United States, progress on the infrastructure package is expected to help gauge fiscal support for the next leg of recovery in the world's largest economy.

The rapid spread of the Delta variant has pushed cases and hospitalizations to a six-month high, with COVID-19 cases averaging 100,000 for three days in a row - up 35% over the past week. 

"We are sort of in a holding pattern. The Delta variant is sort of causing investors to sit on their hands and not really do anything with their portfolios at this point," said Sam Stovall, chief investment strategist at CFRA.

Investor focus is also on inflation numbers due later this week for hints about the path of Federal Reserve policy, after two Fed officials said on Monday inflation was already at a level that could satisfy one leg of a key test for the beginning of rate hikes.

The S&P 500 and the Dow closed lower on Monday, weighed down by a fall in oil stocks and concerns of a sooner-than-expected Fed tapering.

But rising U.S. Treasury yields lifted financial shares, keeping Wall Street's benchmark indexes near record highs.

"We've been seeing the participation of the market narrow, and that usually is an indication of some sort of digestion that is likely to occur. We need to reset the dials before moving significantly higher," Stovall said.

At 8:19 a.m. ET, Dow e-minis were down 19 points, or 0.05%, S&P 500 e-minis EScv1 were up 0.5 points, or 0.01%, and Nasdaq 100 e-minis NQcv1 were up 17.25 points, or 0.11%.

Energy firms ExxonMobil Corp, Chevron Corp, Occidental Petroleum Corp, Marathon Oil Corp and Diamondback Energy Inc rose between 0.7% and 1.4% in premarket trading, tracking a recovery in oil prices from a three-week low. 

AMC Entertainment jumped 9.1% after beating second-quarter revenue estimates as moviegoers returned to its theaters after a year of closures and restrictions. 

Kansas City Southern gained 6.8% after Canadian Pacific Railway Ltd raised its offer for the U.S. railroad operator by about $2 billion to $27.29 billion. 

SVB Financial Group slipped 3.8% on a discounted $1.25 billion equity offering.

(Reporting by Devik Jain in Bengaluru; Editing by Aditya Soni and Subhranshu Sahu) ((Devik.Jain@thomsonreuters.com; within U.S. +1 646 223 8780; outside U.S. +91 80 6182 2062; ;))