WASHINGTON, Nov 1 (Reuters) - Two months after letting a near-total ban on abortion in Texas take effect, conservative U.S. Supreme Court justices on Monday signaled they are reconsidering their positions and could let abortion providers pursue a bid to invalidate the law. The court on Sept. 1 declined to halt the law in a 5-4 decision with all but one of its six conservative justices in the majority. During three hours of oral arguments on Monday, at least two of the justices who had allowed the law to be enforced - Brett Kavanaugh and Amy Coney Barrett - appeared to lean toward permitting abortion providers to proceed with their legal challenge. The court"s conservatives seemed more skeptical about whether to let Democratic President Joe Biden"s administration pursue its own challenge. The Justice Department sued Texas in September seeking to block the Republican-backed law. The administration and abortion providers have said the law violates a woman"s constitutional right to terminate a pregnancy recognized in the court"s landmark 1973 Roe v. Wade ruling and is impermissibly designed to evade federal judicial review. The law imposes the nation"s toughest abortion restrictions, banning it after about six weeks of pregnancy - a time when many women do not realize they are pregnant - with no exceptions for pregnancies resulting from incest or rape. It is one of a wave of Republican-backed state abortion laws in recent years. Abortion opponents hope the court"s 6-3 conservative majority will pare back abortion rights or even overturn Roe v. Wade. Some justices signaled that existing Supreme Court precedent could accommodate the lawsuit by the abortion providers despite the law"s novel design that makes it difficult for federal courts to block it. The law lets private citizens rather than state officials enforce it through lawsuits against providers and others who assist a woman in obtaining an abortion. Depending on what approach the justices take, they could block the law entirely or pave the way for a lower court judge to do so. If the justices keep federal courts out of the process by virtue of the law"s design, it could be replicated in various other states seeking to curtail abortion access. U.S. abortion rights are hanging in the balance as the justices review the Texas law before hearing arguments on Dec. 1 over the legality of a Mississippi measure, blocked by lower courts, prohibiting the procedure after 15 weeks of pregnancy. "FULLY AIRED"Barrett asked clinic lawyer Marc Hearron about whether under the law"s structure the constitutional claims on the right to abortion could ever be "fully aired." Under the law, abortion providers can bring up that constitutional issue as a defense only after they have been sued. Kavanaugh expressed interest in an outcome raised by liberal Justice Elena Kagan in which state court clerks would be barred from allowing lawsuits brought by private individuals seeking to enforce the law to proceed while litigation over the legality of the measure unfolds. Kavanaugh wondered if states could pass similar laws infringing on other constitutional rights including gun rights. A state, for example, could allow for $1 million in damages against anyone who sells an AR-15 rifle, he said. Kavanaugh also wondered about closing a loophole "exploited" by the Texas measure in the court"s precedents concerning when state officials can be barred from enforcing unconstitutional laws. His tone was more skeptical toward the Biden administration lawsuit, telling U.S. Solicitor General Elizabeth Prelogar that challenge was "different and irregular and unusual." Kagan said the law was written by "some geniuses" to evade the broad legal principle that "states are not to nullify federal constitutional rights." Kagan warned of the consequences of states passing laws that infringe upon rights, including same-sex marriage and religious liberty. The Texas measure enables private citizens to sue anyone who performs or assists a woman in getting an abortion after cardiac activity is detected in the embryo. That feature made it more difficult to directly sue the state. Individual citizens can be awarded a minimum of $10,000 for bringing successful lawsuits under the law. Biden"s administration has called it a "bounty." Conservative justices Clarence Thomas and Samuel Alito asked whether anyone would have standing to sue under the law without having a direct injury. Texas Solicitor General Judd Stone, defending the law, said personal "outrage" toward abortion would be enough to justify a lawsuit. The law has deterred abortion providers facing innumerable potentially costly lawsuits in Texas - the second most-populous U.S. state behind only California, with about 29 million people. The court agreed to take up the matter on Oct. 22, bypassing lower courts considering the challenges.