Two U.S. senators are expected to introduce this week sanctions on the Nord Stream 2 natural gas pipeline that Russia is trying to finish, but which Washington has opposed since the Obama era, a source familiar with the matter said on May 29.

The sanctions, which would have to pass Congress and be signed by President Donald Trump, are expected to be introduced as soon as June 1 by Sens. Ted Cruz (R-Texas), and Jeanne Shaheen (D-N.H.).

The senators’ offices did not respond to requests for comment. Last week, however, both senators indicated they were weighing sanctions on Nord Stream 2, led by state gas company Gazprom, as Russia moves closer to completing the project.

Late last year, sanctions sponsored by Cruz and Shaheen halted work by Swiss-Dutch company Allseas on the pipeline that aims to double the capacity of an existing line sending Russian gas to Germany.

Now a Russian pipe-laying vessel aims to finish the remaining 100 miles of the project, which would bypass Ukraine by sending gas to Germany under the Baltic Sea. The pipeline could be launched by the end of 2020 or early next year, Russian President Vladimir Putin has said.

Washington has opposed the project, which would tighten Putin’s economic and political grip over Europe.

Kremlin spokesman Dmitry Peskov said after the Reuters story about senators weighing new sanctions that Moscow considers such measures unfair competition and contradictory to international law.

Cruz told the Atlantic Council think tank this month that new sanctions would apply to any ship or any owner who attempts to finish the project. Ship officers would lose their ability to come to the United States and all their assets would be blocked, he said.

Nord Stream 2 did not immediately respond to a request for comment.