Washington (CNN) - Senior Senate Democrats, including Majority Leader Harry Reid, cautioned Monday that any U.S. move toward sanctions against Russia over Ukraine should be carried out in accordance with European allies.
Separately, Republican Ron Johnson, a member of the Senate Foreign Relations Committee, said he's urging fellow lawmakers to speak with "one voice" as they discuss action over the developing situation in Crimea.
The situation in Ukraine – as it applies to politics in the United States – is not clear yet. Reflexive partisanship, so sharply evident on domestic issues, isn’t always embraced quickly or uniformly on matters of state.
Though, some vocal conservatives amplified their criticism of President Barack Obama’s foreign policy as Russian troops moved to consolidate their hold on Crimea and the administration moved quickly to put together a plan for possible sanctions.
Obama warned Monday that the range of steps under consideration would “isolate” Russia.
One senior U.S. official said decisions are "expected very soon" and it could be a "pretty fast process."
Some European allies, particularly Germany and France, are balking at sanctions before giving diplomacy a chance.
And Reid believes any action along these should not be arrived at unilaterally.
"What I'm going to recommend is that anything we do be coordinated with our allies. President Obama says he wants to give economic aid, I think that's appropriate. Happy to help in any way."
A source told CNN Reid was speaking for himself, not the administration, regarding his views on the United States being in agreement with European leaders.
Sen. Patrick Leahy, a Democrat from Vermont and the most senior member of the Senate, warned that United States has "few options" to punish Russia and those can only work if "we can get our allies to stick with us."
Leahy, who chairs the appropriations subcommittee on foreign operations, said when people push Obama to act quickly, it "raises expectations" but in reality "there's very little we can do."
"We can support Ukraine. We can help with aid. We can do these things. But if there is going to be a shooting war between the Ukrainians and the Russians in Crimea, we're not sending troops in," Leahy said. "But no other country is going to send troops in."
Congress will have a say in the focus and size of a U.S. response, with calls already for a possible sanctions package.
Hawkish Republicans have criticized Obama for what they called a lack of resolve that they say emboldened Russian President Vladimir Putin to send troops into the Crimea region.
Sen. John McCain, an Arizona Republican, called Obama's foreign policy "feckless" on Monday, after House Intelligence Committee Chairman Mike Rogers of Michigan said on "Fox News Sunday" that Putin and Russia had been "running circles around us."
Fellow GOP Sen. Lindsey Graham of South Carolina called for reviving plans for a NATO missile defense shield in Poland that Russia opposed.
Obama told reporters on Monday that there should be "unanimity" between Democrats and Republicans in seeking to preserve "the principle that no country has the right to send in troops to another country unprovoked."
"My expectation is we ought to be able to get Congress to work with us to achieve that goal," he said, specifically calling for an economic assistance package for Ukraine to help provide stability during the crisis.
Sen. Robert Menendez, who chairs the Senate Foreign Relations Committee, responded later that the panel was putting together legislation to provide $1 billion in loan guarantees for Ukraine's economy.
"We are also consulting with the administration on possible sanctions actions against individual Russians and Ukrainians that range from visa bans and asset freezes, to the suspension of military cooperation and sales, as well as economic sanctions," the New Jersey Democrat said.
Johnson told CNN he was urging the panel to speak with "one voice" to "show the Russians” unanimity.
"It will send a much more powerful signal and hopefully get Putin to think twice," Johnson said, adding that "Putin needs to pay a big price here" because "this is no time to be shrinking violets and rely on words."
CNN's Dana Bash, Ted Barrett and Dana Davidsen contributed to this report.