WASHINGTON--Congressional leaders backed President Obama's warning Friday that "there will be costs" of any Russian military intervention in Ukraine, and pledged to provide support for the embattled former Soviet state as tensions rise in the region.

In the days ahead, Rep. Eric Cantor (R-Va.), the majority leader, said "Congress will be looking for ways to help bolster the Ukrainian government's efforts to stabilize the economy, restore their sovereignty, and promote political reconciliation."

And a bipartisan coalition of 12 leaders from the Senate Foreign Relations Committee, including Sen. John McCain (R-Ariz.) and Sen. Marco Rubio (R-Fla.), backed the White House in a letter late Friday to Obama.

"We write in support of the administration's efforts to help Ukraine to consolidate democratically elected government, preserve its territorial integrity, and enjoy the freedom to exercise a sovereign decision to sign and implement an Association Agreement with the European Union," the senators said in their letter.

"We are prepared to work with your Administration to reinforce your efforts by authorizing U.S. loan guarantees to Ukraine and increasing assistance to facilitate a peaceful transition of power. We also believe that the U.S. should make use of the tools at its disposal, including targeted sanctions."

But even as the president consolidated support from both his allies in Congress, as well of some of his detractors among the Republican defense hawks, other lawmakers were more critical. Some said the White House's reluctance to take a hard line against Russia in the past led to the escalation of tensions Friday in the Crimea region of Ukraine.

House Speaker John A. Boehner (R-Oh.) said U.S. allies have feared that "our acquiescence and, in some cases, silence in the face of Russia's systemic and persistent meddling in the affairs of its neighbors" would "embolden Russia to take additional and escalatory aggressive action. Those fears have been confirmed today."

And Sen. Lindsey Graham (R-S.C.), a top foreign policy hawk, tweeted that "statements by the Obama Admin regarding grave consequences & crossing lines are now falling on deaf ears."

Rep. Adam Schiff (D-Burbank), a top Democrat on foreign policy issues, said "Congress stands ready to work w/ President & European allies to impose substantial costs on #Russia for violations of Ukrainian sovereignty," in a tweet following the president's remarks in the White House briefing room.

"Glad POTUS finally issued warning to Russia-there will be costs for intervention," tweeted Sen. Kelly Ayotte (R-N.H.). "Time to reset the Reset."

And Sen. Rand Paul, (R-Ky.) warned that "Russian intervention in Ukraine would be dangerous for both nations, and for the rest of the world."

lisa.mascaro@latimes.com

Twitter: @lisamascaroinDC