WASHINGTON (Reuters) - Supreme Court justices appeared reluctant on Tuesday to endorse a conservative challenge to the way Texas draws state legislative districts in a case that could shrink the political clout of Hispanics and boost the power of rural voters.

The U.S. Supreme Court is pictured in Washington June 8, 2015. REUTERS/Gary Cameron

It was not clear after an hour of oral arguments how the nine justices would rule in a dispute that questions a process that all 50 states employ to create electoral districts: using an area’s total population as opposed to just eligible voters.

The case is closely watched because of its potential to transfer influence from urban areas that tend to be racially diverse and favor Democrats to rural ones with predominantly white voters who often back Republicans.

Two Texas voters recruited by a conservative legal activist group contend that the process Texas uses to draw electoral districts violates a long-established legal principle of “one person, one vote” endorsed by the Supreme Court in the 1960s.

If their challenge succeeds, it would upend how voting maps are drawn around the country.

Counting everyone and not just eligible voters boosts the electoral influence of locales, typically urban, with sizable populations of people, often Hispanics, ineligible to vote, including legal and illegal immigrants as well as children.

It was uncertain how conservative Justice Anthony Kennedy, who often casts the deciding vote in close cases, would vote. Kennedy and conservative Chief Justice John Roberts questioned why it should be difficult to ensure equal representation while also protecting the rights of individual voters.

“Why can’t you have both?” Kennedy said.

It may not be practically feasible to do so because states would have to “disregard many other traditional redistricting factors,” responded Scott Keller, the lawyer for Texas, a reliably conservative and Republican-governed state that is fending off this conservative legal challenge.

Kennedy appeared to concede Keller’s point, saying the Texas lawyer’s explanation “sounds highly probable.”

The court’s liberals appeared eager to keep the existing system. Justice Sonia Sotomayor raised concerns that a new system would be difficult to implement when compared with U.S. census numbers currently used. She said one method cited by the challengers is “flawed on many levels.”

‘PROTECT VOTERS’

Roberts appeared to downplay the potential disruption of drawing districts based on the population of eligible voters, saying although all states currently use total population “it seems to me that there will be a lot of areas where ... it’s not going to make a difference.”

At another point, Roberts said, “It is called ‘one-person, one-vote.’ That seems to be designed to protect voters.”

The Obama administration backed the Texas plan.

The challengers said the state Senate redistricting map signed into law in 2013 did not equally distribute voters, improperly inflating the voting power of urban areas.

The Project on Fair Representation, the conservative group that recruited plaintiffs Sue Evenwel and Edward Pfenninger, also initiated a lawsuit that in 2013 led the high court to invalidate a portion of the 1965 Voting Rights Act requiring federal approval for election law changes in states with histories of racial discrimination.

The group also brought a case challenging the use of racial preferences in university admissions that the Supreme Court will hear on Wednesday.

The court on Tuesday also heard a related case from Arizona. The justices appeared closely divided as they considered whether state electoral districts drawn for the 2012 election benefited Democrats by consolidating large numbers of Republican voters in certain districts.