NEW YORK (TheStreet) -- Oil prices hit a three-month low on Monday as investors doubt that OPEC will actually pass the deal it first announced in September, which would cut production to help ease the global oil glut problem.

But RBC Capital Markets remains "maybe the lone OPEC optimist," the firm's Head of Global Commodity Strategy Helima Croft said on CNBC's "Power Lunch" this afternoon. 

"It is imperative to reach a consensus between OPEC nations," Saudi Arabia's oil minister Khalid al-Falih said over the weekend. 

This comment from al-Falih was "very important" because he's saying, "Let's get this done," Helima said. "If Saudi backs off, then no deal. But as long as Saudi wants this deal done and they're driving the bus, we think it gets done."

"Aren't Iran and Iraq the two big wild cards?" CNBC's Brian Sullivan asked.

Iraq is fighting with the Kurds internally about their numbers, while Iran has ramped up production and is back to where it was before sanctions hit it, she said. However, Iran may not be able to get much more done without foreign investment.

This is where the election of Donald Trump to presidency last week becomes "very, very important," Helima claimed. "Are European energy companies going to go back into Iran and help Iran lift their production significantly from where they are now if they're facing the potential snapback of sanctions?"

RBC Capital Markets says the OPEC deal gets passed and we see oil prices rise past the $50-mark, she said.

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