Shimmers of economic optimism from the United States and growing support for production caps gave crude oil prices a lift above $40 per barrel Thursday.

Brent and West Texas Intermediate, the global and U.S. benchmark prices for crude oil, respectively, rallied strongly Wednesday amid growing support for a cap on output from major oil producers.

Russian Energy Minister Alexander Novak, a strong supporter of the production freeze, said a balance between supply and demand would return by late 2016 if an agreement is reached during planned negotiations next month in Doha.

Crude oil prices are off from the peak levels of 2014 above $100 per barrel because supplies outweigh demand in a global economy struggling to gain momentum.

Brent gained 1 percent at the start of the trading day in New York to $40.74 per barrel, holding steady after slipping earlier this week on the back of Iranian reluctance to back production agreements. WTI gained 1.5 percent to open at $39.05 per barrel.

Strong momentum into the mid-$40s may be stifled by ongoing economic pressures. U.S. Federal Reserve Chair Janet Yellen said she was somewhat optimistic about the pace of growth for the U.S. economy, but said a soft pace of advancements overseas could throttle any substantial forward momentum.

Eurostat, the statistics office for the European Union, reported regional annual inflation for February turned negative after recording 0.3 percent for January. "In February 2016, negative annual rates were observed in fifteen member states," it said.

Russia's energy minister said Thursday there may be a ceiling for crude oil prices this year. Anything more than $60 per barrel short-term would trigger a rush in investments and potentially push markets further toward the supply side, "which in its turn will lead prices down."