A night of DNC speeches under a magnifying glass

President Barack Obama and Vice President Joe Biden spoke Thursday night about the economy, energy policy, Medicare and Afghanistan, as they accepted their nominations at the Democratic National Convention in Charlotte, N.C.

Here is a closer look at some of their assertions: MANUFACTURING Mr. Obama, in his acceptance speech, said, “We can help big factories and small businesses double their exports, and if we choose this path, we can create a million new manufacturing jobs in the next four years.”

Looking at current trends, it is certainly possible: The nation has added about 222,000 manufacturing jobs in the past year. Moreover, the Obama campaign has several proposals to encourage manufacturers to add workers.

But there is a bigger economic story behind the gains in manufacturing. For three decades, manufacturers had cut jobs, and then when the recession hit, they slashed hundreds of thousands more. Now, some economists say, they might be adding workers to simply regain some lost capacity.

American workers’ wages have also been stagnant for more than a decade and, in many cases, have declined during the recession. Over the same period, pay climbed in many other countries, making American workers’ wages more competitive. Strong blue-collar wage growth here or lower wages in foreign countries would send more jobs back overseas, economists say.

Mr. Obama also repeated his promise to double exports, to about $3.2 trillion a year in 2014 from about $1.6 trillion in 2009. He is roughly on track to meet that goal, with exports running at an annual pace of $2.2 trillion, judging by data from the first half of the year.

But Mr. Obama got help by starting the clock during the depths of the recession in 2009, when global trade dipped and U.S. exports fell. And the strength of the dollar against other currencies — a factor almost entirely outside of U.S. politicians’ control — will mainly determine export growth in the short term, economists argue.

— Annie Lowrey

ENERGY Mr. Obama, seeking to capitalize on energy trends for which his administration is only partly responsible, announced that he was setting a goal of cutting “our oil imports in half by 2020, and support more than 600,000 new jobs in natural gas alone.”

He intends to achieve that goal by increasing domestic oil and gas production, mandating increases in autos’ and trucks’ fuel economy, substituting ethanol and other alternative fuels for gasoline, streamlining regulation and converting trucks and buses to run on natural gas.

But the campaign said the administration would continue to lease public lands and offshore areas for drilling, including in the Arctic Ocean off Alaska. Industry groups contend that the administration has held back oil development on public lands, and that most of the increased production is coming from private property.

A campaign document says the president is using 2008 as a baseline for the reduction in imports, allowing him to claim credit for several years of declining demand for fuel because of the recession and leasing and production decisions made by former President George W. Bush’s administration.

The president’s projections are in line with those of government and independent analysts, who say that if current trends continue, imports will decline to levels not seen for decades, even without additional policy changes.

— John M. Broder

MEDICARE Mr. Biden criticized the Romney campaign on Medicare, saying, “What they didn’t tell you is what they’re proposing would cause Medicare to go bankrupt by 2016.” But the actions he described would not end Medicare in four years.

At issue is the Medicare trust fund, which is fed by payroll taxes, and what would happen to it if Mr. Obama’s health care law were to be repealed, as the Republicans have vowed to do.

The trust fund’s solvency has long been in question. Mr. Obama’s health care law extended its solvency by curbing the growth of projected spending — the $716 billion Medicare cut that has been debated in the campaign — and by raising some revenues. As the 2011 annual report of the Medicare trustees put it, the financial status of the “trust fund is substantially improved by the lower expenditures and additional tax revenues instituted by the Affordable Care Act.” Absent those savings, the trust fund will be exhausted sooner.

What would happen then? The most recent report states: “If assets were exhausted, Medicare could pay health plans and providers only to the extent allowed by ongoing tax revenues — and these revenues would be inadequate to fully cover costs. Beneficiary access to health care services would rapidly be curtailed.”

But it adds that, in practice, Congress has never allowed the trust fund to become depleted.

— Michael Cooper

AFGHANISTAN “In 2014, our longest war will be over.” That is what Mr. Obama said Thursday about Afghanistan.

Well, maybe. That is the deadline for pulling out all U.S. and other foreign troops. But the White House has said it envisions an “enduring force” in Afghanistan for years to come that could amount to 10,000 to 15,000 troops. They would not be in combat, but they would be there to stop the Taliban from overtaking Kabul, the capital, and to keep Pakistan from losing control of its 100 or so nuclear weapons.

The United States’ combat role may soon be over; it is less likely the war will be.