NEW YORK (TheStreet) -- Oil prices may be holding around $50 for now, but they will see a sharp drop if OPEC can't come to an agreement, The Gartman Letter's Editor Dennis Gartman said on CNBC's "Power Lunch" on Thursday afternoon. 

The odds for an OPEC deal are at 60%, Macquarie Capital said in a note released earlier today, CNBC's Melissa Lee reported.

"I think they're a bit high," Gartman said. The capability of OPEC to approve a deal are lower for a number of reasons.

Russian oil producer Rosneft (RNFTF) wants to produce as much as it can, Nigeria has financial problems, Venezuela has production issues, Iran wants to increase production, and the Chinese are "removing themselves from the market," Gartman said. 

"I think it's going to be very difficult - even if they get an agreement - to put prices very much higher at all, if at all," he noted. 

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If a deal doesn't happen, how much of a "premium in the price per barrel is embedded right now for OPEC?" Lee asked. 

"I think that all of the price of a potential agreement that might be adopted has been put in," Gartman replied. 

If OPEC doesn't come to an agreement, investors can expect oil to be trading around $46."It'll go down very fast," he explained. 

Whether the news is positive or negative, oil prices will probably stick between $40 and $50 for now, Gartman predicted. 

"That's not such a bad thing for producers or consumers. That might be the best of all worlds to be honest," he added. 

OPEC has its next formal meeting on November 30.