WASHINGTON — Americans are divided along party lines on U.S. military action against Iran, according to polls conducted since the war began, with most polls showing opposition is higher than support.

Polls suggest that many Americans are worried the military action is making the U.S. “less safe,” even as they see Iran as a threat to U.S. security. There are also warning signs for President Donald Trump as he confronts the possibility of a prolonged conflict that could come with significant economic turmoil. Trump gave conflicting messages on Monday about the war’s timeline, suggesting it could be near its end while also threatening additional force against Iran if the country disrupted the global flow of oil.

Fluctuating oil prices may already be alarming voters. Polls conducted over the weekend found a large majority of Americans are worried about the war causing oil and gasoline prices to rise. The vast majority expect the U.S. action against Iran will last at least “months,” if not longer.

Republicans are largely behind the president, a Republican, the polls show, but there are indications that they are wary of any response that would lead to U.S. troops on the ground in Iran. And after Trump campaigned on the pledge of putting “America first” and ending U.S. involvement in “forever wars,” the Iran conflict could become a particular point of friction.

About half of registered voters — 53% — oppose U.S. military action against Iran, according to a new Quinnipiac Poll conducted over the weekend. Only 4 in 10 support it, and about 1 in 10 are uncertain. A new Ipsos poll also found more disapprove than approve of the strikes.

That’s similar to the results of text message snap polls from The Washington Post and CNN, both conducted shortly after the joint U.S.-Israel attacks began, which also indicated that more Americans rejected the military action than embraced it.

A recent Fox News poll found opinions more evenly divided: Half of registered voters approved of the U.S. military action, while half disapproved.

Several of the recent polls show a majority of Americans believe the Trump administration has not provided a clear explanation of the reasons behind the military strikes, and there are some divisions about whether Iran truly posed an “imminent and direct threat” to the United States, as the White House has said.

Most voters in the Quinnipiac poll — 55% — said they did not believe Iran posed an “imminent military threat” to the U.S. before the current military action. On the other hand, about 6 in 10 registered voters in the Fox News poll said Iran poses a “real national security threat,” and a recent AP-NORC poll found about half of U.S. adults were highly concerned that Iran’s nuclear program posed a direct threat to the U.S.

As oil prices oscillate, the vast majority of voters are “very” or “somewhat” concerned about oil and gasoline prices rising in the U.S., according to the Quinnipiac poll. Only about one-quarter of voters are “not so concerned” or “not concerned at all.”

The highest levels of concern are driven by Democrats and independents, but about half of Republicans are also at least somewhat concerned about the war increasing gas prices.

About two-thirds of Americans expect U.S. gas prices will “get worse” over the next year as a result of the U.S. military action, according to the Ipsos poll conducted March 6-9. Republicans were more likely to say gas prices would worsen than improve as a result of the war: 44% said they would get worse, while 26% expected they would improve. About 2 in 10 thought they would remain the same. Democrats and independents overwhelmingly expect gas prices will worsen.