Can Trump run a war and a midterm campaign at the same time?

Can President Donald Trump run a war and a midterm campaign at the same time?

He is discovering just how difficult that can be.

In week two of the biggest military operation of his presidency − a conflict that already has ensnared the Persian Gulf states and NATO − the repercussions of rising oil prices are stoking his biggest political problem at home.

That push-and-pull has contributed to mixed messages the White House has been sending now, and it will complicate crucial decisions ahead.

For instance: How long will the war last?

"It's going to be finished pretty quickly," Trump first told GOP lawmakers March 9 at a retreat at a Trump golf club near Miami. He described the conflict as "a short-term excursion."

That was good news for Republicans who are running in November. The president's reassurance that the war would end "very soon" calmed turbulent energy markets that were driving up the price of gas.

But those words were also welcome in Tehran. "Iran, unlike the United States, has prepared itself for a long war," Ali Larijani, secretary of Iran's Supreme National Security Council, has taunted on social media.

In his next breath, though, Trump threatened escalation. If Iran tries to stop the world's oil supply, a fundamental part of Tehran's strategy, "they'll get hit at a much, much harder level," he warned. Hours later, U.S. forces began what Pentagon chief Pete Hegseth called "our most intense day of strikes inside Iran."

Is that clear?

"We've already won in many ways," the president said, "but we haven't won enough."

A complicated calculation

Though interests overlap between Trump and Republican candidates, between war and politics they aren't always the same.

For the president, upending the Islamic Republic, which has bedeviled the United States since it ousted the shah of Iran in 1979, would be a legacy-making achievement. Iran has become the leading state sponsor of terrorism, including against Americans, and harbors nuclear ambitions.

But the Iranian regime has more will and more weapons than, say, Venezuela, where a U.S. special-ops team in January summarily captured President Nicolás Maduro. Since then, the administration has been able to negotiate a working relationship with the government he left behind.

In contrast, Tehran has responded to the joint U.S.-Israeli assault by raining down drones and bombs across the region. It has effectively closed the crucial Strait of Hormuz. And it has installed as its new supreme leader the son of the one the U.S.-Israeli assault killed.

Prosecuting this war, especially over time, is all but guaranteed to drive up the cost of energy, which in turn would mean higher prices for everything from fertilizer to groceries. Economists warn it could risk sparking stagflation, a combination of high inflation and high unemployment, or even a recession.

Those economic worries were at the top of votes' priorities in an NBC News poll released March 8 − and they were where voters gave Trump his lowest approval rating, at 36%.

His rating on handling Iran was only slightly better, at 41%.

The president has been accused of failing to build public support for the war before it started and not articulating clear goals that would allow it to end.

"Look, here we are, well into the second week, and it is still the case that the Trump administration cannot explain the reasons we entered the war, the goals we're trying to accomplish and the methods for doing it," Sen. Elizabeth Warren, a Massachusetts Democrat, told reporters March 10 as she left a classified administration briefing to the Armed Services Committee.

Trump has said the goals are ending Iran's nuclear capabilities for good, destroying its navy and annihilating its missiles. But he has also said the United States should have a role in choosing its new leader and promised to support Iranian protesters trying to overthrow the government. He has suggested he might be open to deploying U.S. ground troops.

There could be value in that ambiguity about his bottom line. He could have more leeway to declare what victory was and when it had been achieved − though the United States inevitably will bear some responsibility for whatever happens next in the region.

"It's not for me to posit whether it's the beginning, the middle or the end" of the war, Hegseth told reporters at the Pentagon. Trump "gets to control the throttle," he said.

For some House Republicans, it's up to Trump

For congressional Republicans, their political fate was already in Trump's hands.

Presidents aren't on the ballot in midterm elections, but voters' judgments on how they're doing has been the most important single factor determining which party wins competitive seats.

Consider this: Only 30% of registered voters had a positive view of the Democratic Party in the NBC poll. Even among Democrats, just 62% approved of their party.

Even so, by 50%-44% Americans said they wanted Democrats to regain control of Congress in the midterms − less an endorsement of Democrats than a rejection of Republicans.

The pessimism of GOP incumbents is apparent in their decisions about whether to stick around. So far, 35 House Republicans have announced they aren't running for another term, compared with 21 Democrats.

Democrats need to flip just three seats to regain control of the House, and with that the standing to chair committees, pass legislation, launch investigations and issue subpoenas. To impeach, too.