One in a series of stories examining the positions of the major presidential candidates.

WASHINGTON (CNS) — This November, voters in a handful of states across the country will decide if state law should uphold traditional marriage or allow same-sex marriage.

Four states — Maine, Maryland, Washington and Minnesota — have ballot initiatives on the issue.

Supporters are hoping for victory in those states, saying it could be the start of a new momentum for legalizing same-sex marriage — which in previous years has lost more than 30 ballot initiatives.

Opponents of same-sex marriage say legalizing such unions undermines traditional roles of marriage and family.

The U.S. Catholic bishops, in their document “Forming Consciences for Faithful Citizenship” — which outlines church teaching on contemporary issues for Catholic voters — states that “marriage must be defined, recognized, and protected as a lifelong commitment between a man and a woman, and as the source of the next generation and the protective haven for children.”

So far, the economy, the budget, Medicare and the health care law have been the focus of the presidential race and whether same-sex marriage is an issue that will carry much weight remains to be seen.

Former Massachusetts Gov. Mitt Romney, the Republican candidate, and President Barack Obama, the Democratic candidate, hold opposite views on legalizing same-sex marriage, as do the platforms of their respective political parties.

Romney has stressed the need to preserve traditional marriage between one man and one woman. In May, Obama announced his support for same-sex marriage as a matter of civil rights, but polls have shown that his stance on this issue has had little effect on people’s voting plans.

The GOP platform calls the institution of marriage the “foundation of civil society.”

“Even as we believe that marriage, the union of one man and one woman must be upheld as the national standard, a goal to stand for … we embrace the principle that all Americans should be treated with respect and dignity,” it said.

The Democratic Party platform says it supports “marriage equality” and “the movement to secure equal treatment under law for same-sex couples.” It also supports repealing the Defense of Marriage Act and passage of the Respect for Marriage Act.

The party platform also stressed the need for “churches and religious entities to decide how to administer marriage as a religious sacrament without government interference.”

Earlier this year, laws were passed in Washington state and Maryland to legalize same-sex marriage, but opponents in both states gathered enough signatures to force a referendum on the law, placing it before voters this November.

Archbishop J. Peter Sartain of Seattle and Bishop Blase J. Cupich of Spokane, Wash., released video statements urging Washington Catholics to reject the bill to legalize same-sex marriage in their state.

In early September, the Washington Catholic Conference, the public policy arm of the state’s bishops, published a pastoral statement on the referendum. If the new marriage law is accepted, it said, the civil meaning of marriage would be lost and replaced by a “genderless contract without reference to children.” It also said the “foundational nature of marriage for the good and the strength of human society will be harmed beyond repair.”

The statement stressed that the bishops’ support for traditional marriage “is not born out of bias or intolerance toward anyone” and hoped the vote on the issue would provide an “opportunity to debate this social issue in an atmosphere of respect, honesty and conviction.”

In a letter to Catholics in his diocese, Bishop Cupich urged that debate on the issue be “marked by civility and clarity.” He noted that the law would not create any new legal rights for same-sex couples since the state already extends rights to registered domestic partners.

He also stressed the vote could be a “major shift in an institution that serves as the foundation stone of society.”

In Minnesota, where a constitutional amendment to ban same-sex marriages comes before voters in November, Archbishop John C. Nienstedt of St. Paul and Minneapolis has urged Catholics to “stand up for the truth, always with love,” especially when it may be difficult.

In an Aug. 30 column in The Catholic Spirit, archdiocesan newspaper, he said the church’s “effort to support God’s unchanging plan for marriage is not a campaign against anyone but rather a positive effort to promote the truth about marriage as a union between one man and one woman.”

He also stressed that ensuring this definition of marriage remains intact “does not take away anyone’s existing rights or legal protections.”

In Maine, the same-sex marriage issue in this election is whether to keep in place a 2009 ballot measure that banned same-sex marriage after the state legalized same-sex marriage.

Currently, six states and the District of Columbia allow same-sex couples to marry. Thirty states have constitutional amendments banning same-sex marriage; some of those also prohibit civil unions and other approaches that grant legal rights to such couples. Twelve states permit civil unions.