After weeks of negotiation, House and Senate leaders agreed late Monday on new measures targeting Iranian shipping, not only of oil but also of a wide variety of other products. The House was set to vote as soon as Wednesday, while the Senate leaders — Mitch McConnell, the Republican minority leader from Kentucky, and Harry Reid, the Democratic majority leader from Nevada — also signaled that they would move the legislation forward quickly.

“The idea is to up the ante to the greatest extent possible,” said Senator Ron Wyden, Democrat of Oregon. “From a foreign policy standpoint, trying to find every possible way to up the ante makes sense.”

Mark Dubowitz, the executive director of the Foundation for Defense of Democracies and a supporter of tougher sanctions, said the new measures were “a major upgrade of the sanctions regime.” But he noted that the goal of the sanctions is to change the political calculus of Iran’s leadership, increasing pressure to the point that it agrees to resolve concerns about whether its nuclear program is peaceful, as it insists, or aimed at producing a bomb, as many experts contend.

“There’s no evidence to date that the sanctions have achieved that objective,” he said.

Administration officials took pains to point out the economic damage the sanctions have inflicted on Iran. European and American sanctions have driven down its oil exports by 40 percent to 50 percent, depriving Iran of $9 billion in revenue every quarter, said Robert J. Einhorn, the State Department’s special adviser on nonproliferation.

Iran’s currency, the rial, has lost 38 percent of its value since the sanctions law was passed last January.

“These sanctions are really beginning to sink in,” said Benjamin J. Rhodes, a deputy national security adviser, who quoted Iran’s president, Mahmoud Ahmadinejad, as saying they were the toughest sanctions Iran had ever faced.

Most measures announced Tuesday seek to close loopholes in earlier sanctions. The United States will now blacklist any financial institution that receives payments for Iranian oil, which will prevent Iran from using foreign banks or its national oil company, in lieu of the Central Bank of Iran, as an agent to process oil transactions.