WASHINGTON (Reuters) - Republican and Democratic U.S. lawmakers said on Thursday they would keep up their push for tougher sanctions on Turkey over its offensive in Syria despite the announcement of a five-day ceasefire.

Republican Senator Lindsey Graham and Democratic Senator Chris Van Hollen announced legislation that would impose “crippling” sanctions on the government in Ankara shortly before U.S. Vice President Mike Pence and Turkish President Tayyip Erdogan said Turkey had agreed to a pause to let Kurdish forces withdraw from a “safe zone.”

The bill would target Turkish officials, end U.S. military cooperation with the NATO ally and mandate sanctions over Turkey’s purchase of a Russian S-400 missile defense system.

Leaders of the Senate Foreign Relations and House of Representatives Foreign Affairs committees also unveiled sanctions measures with bipartisan support on Thursday, with many of the same provisions.

None of the lawmakers sponsoring the bills planned to abandon them, saying they viewed the threat of tough sanctions as leverage to ensure that Turkey complied with the ceasefire and left Kurdish areas in northern Syria for good.

“Turkey has legitimate national security concerns within Syria but they cannot be met by invasion and force of arms,” Graham said in a statement.

“Senators Van Hollen and Graham have spoken, and they agree on the need to move full steam ahead with their legislation,” said Bridgett Frey, a Van Hollen spokesman. A spokesman for Graham also said they were going to move ahead.

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Graham predicted his proposal would pass the Senate with enough support - a two-thirds majority - to overcome a possible veto by President Donald Trump.

Representative Eliot Engel, the Democratic chairman of the House of Representatives Foreign Affairs Committee, said it was far too soon to consider abandoning the sanctions push.

“I’m glad there’s a ceasefire. It’s a good sign, but let’s see if it lasts and let’s see what it really means,” Engel told reporters.

REPUBLICANS BREAK FROM TRUMP

Republicans hold a majority in the Senate. Democrats control the House.

Turkey’s incursion into Syria and attacks on the Kurds has marked one of the rare times when congressional Republicans have disputed a Trump policy.

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Announcing the sanctions with Graham, Republican Senator Marsha Blackburn said the bill would not be the last step in Congress’ effort to influence Ankara. “Turkey could stop this right now if they wanted to,” she said.

Normally an ardent defender of fellow Republican Trump, Graham has been harshly critical of the president’s decision to withdraw troops from northeastern Syria, paving the way for a Turkish offensive against Kurdish fighters who until recently were helping U.S. forces fight Islamic State (ISIS) militants.

“Congress is going to speak with a very firm, singular voice, that we will impose sanctions in the strongest measure possible against this Turkish outrage that will lead to the re-emergence of ISIS, the destruction of an ally, the Kurds and eventually benefit to Iran to the detriment of Israel,” Graham told a news conference announcing the bill.

He also said he thought a resolution opposing the offensive in Syria, which passed the House overwhelmingly on Wednesday, would get more than 80 votes in the 100-member Senate, if the chamber’s Republican leaders allowed a vote.

The measure passed the House by 354 to 60. Shortly afterward, Trump and House Speaker Nancy Pelosi exchanged barbs as a White House meeting on Syria policy.

Democrats sought a Senate vote on the resolution on Thursday morning, but were prevented by Republican Senator Rand Paul.

Republican Senate Majority Leader Mitch McConnell said as he opened the Senate Thursday that he wanted a “stronger” resolution than the one passed by the House.