A measure that would change the US Constitution to let Congress ban burning the American flag was sent to the Senate floor today, setting up an election-year debate.
The amendment has already passed the US House of Representatives by the needed two-thirds margin.
The flag debate comes shortly after the Senate defeated a constitutional amendment to prohibit same-sex marriages.
Democrats say Republicans are scheduling votes on a string of similar issues to win support from conservatives who might otherwise not vote in the November congressional elections.
The Supreme Court ruled in 1989 that flag burning was protected under constitutional free-speech guarantees, invalidating laws in 48 states and outraging veterans' groups and others who say that an important national symbol should be protected from defacement.
According to a CNN poll, 56 per cent of American adults support the flag-burning amendment, while 40 per cent oppose it.
The amendment, which must win approval from at least 38 states within seven years, would not prohibit flag desecration but give Congress the power to say how the flag can be protected and what penalties should apply.
The Senate is expected to take up the amendment before the July 4th recess.