For Republicans with presidential ambitions, the turmoil in Ukraine, Syria, Venezuela and other world hot spots has been an occasion to raise their own profiles as players in the foreign-policy debate and to attack President Barack Obama’s leadership.

Florida Sen. Marco Rubio, a potential 2016 presidential candidate, is pushing for policies to isolate Russia financially and diplomatically as punishment for Russian President Vladimir Putin’s use of force in Ukraine. …

Sen. Ted Cruz (R., Texas) called almost immediately for Russia to be expelled from the Group of Eight and possibly from other world councils, such as the World Trade Organization.

But Mr. Cruz also described his own perspective as a middle ground between those in the party calling for a muscular foreign policy, such as Sen. John McCain (R., Ariz.), and the party’s more cautious wing. “I agree with John McCain that we should be a voice for freedom, but I agree with Rand Paul that we should be exceedingly reluctant to employ U.S. military force,” Mr. Cruz told Politico.