Foreign-exchange expert Douglas Borthwick said the dollar may keep dropping.

"We've got another 20% to go before I feel satisfied that the U.S. has reached that weaker dollar policy," Borthwick said during Jim Cramer's latest Trading Strategies roundtable for investors.

The dollar index is now lower than it was before the post-election rally that followed the election of President Donald Trump.

"But it's still not low enough," Borthwick said.

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This article was written by a staff member of TheStreet.