The Supreme Court on Monday ruled against Colorado voters challenging a congressional redistricting plan favorable to Democrats.

In a unanimous decision, the justices said that three Republican voters were not entitled to sue in an effort to replace a redistricting plan ordered by a court with one passed by a Republican-controlled state legislature. The three voters were joined by a former Democratic state legislator who often voted with Republicans.

A Democratic state judge drew up the first redistricting plan in 2002, while the Republican Legislature drew one up in 2003.

The court plan had been put in place when a divided Colorado General Assembly was unable to agree on one in time for the 2002 election.

In their lawsuit, the challengers said the court-imposed map violates a right of citizens under the U.S. Constitution to vote for congressional candidates in districts created by state legislatures.

In an unsigned opinion, the justices said that the only injury the voters allege is that the Elections Clause had not been followed.

"This injury is precisely the kind of undifferentiated, generalized grievance about the conduct of government that we have refused to countenance in the past," the court stated.

The Colorado case is the Supreme Court's latest foray into congressional redistricting battles. Last year, the justices addressed a messy redistricting fight in Texas, ruling that the Constitution does not bar states from redrawing political lines in mid-decade when one party or the other senses an advantage.

The decision grew out of a court review of a Texas redistricting plan orchestrated in 2003 by Tom DeLay, who was a Republican congressional leader at the time.

In the Colorado case, a panel of federal judges last August dismissed the Republicans' lawsuit, saying the same issue had already been decided in an earlier lawsuit brought by the Colorado attorney general.

In that case, the Colorado Supreme Court ruled against the Republican legislative plan in 2003, saying the state constitution restricted congressional redistricting to once per decade and that the legislature's plan was the second plan.

The case is Lance v. Dennis, 06-641.