Bloomberg, Reality Check: Biden Misleads on Impact of Romney’s Tax Plan:

The Claim: Biden said in his prepared remarks that Republican
presidential candidate Mitt Romney “has a new tax proposal — the
territorial tax — that experts say will create 800,000 jobs, all of
them overseas.”

The Background: Romney has proposed changing the basic principles of
the U.S. international tax system. Under current law, companies owe U.S.
taxes on the profits they earn around the world. They receive tax
credits for payments to foreign governments and don’t have to pay U.S.
taxes until they bring the money home. U.S.-based companies with
substantial overseas operations keep profits overseas to avoid taxation
here. Romney wants the U.S. to adopt a territorial tax system under
which companies would owe little or no taxes on their overseas income.

The Facts: Biden overstated the case. His 800,000 jobs number is
based on a study conducted by one expert, Kimberly Clausing, an
economics professor at Reed College in Portland, Oregon. Her July
analysis [A Challenging Time for International Tax Policy, 136 Tax Notes 281 (July 16, 2012)] examined the effects of a “pure” territorial system under which
U.S. companies would face no domestic taxes on their foreign income. …Clausing’s study doesn’t say that no jobs would be created in the
U.S. Instead, it says that a pure territorial tax plan would increase
employment by U.S. companies in low-tax countries.

Biden's claim apparently is based on this paragraph from the article:

Based on my research and that of other experts in
international taxation, it is possible to estimate how
many jobs are at stake in this debate. In 2008 U.S.
multinational firms employed 10 million workers in
affiliated firms abroad. Under a pure territorial tax
system, the tax incentive to locate jobs in low-tax
countries would increase significantly, which I calculate
would increase employment in low-tax countries
by about 800,000 jobs.