The number of Democrats who publicly oppose gay marriage dwindled this week as arguments in two Supreme Court cases drew national attention - and political pressure - to the issue.

In a matter of four days, six Democratic senators issued statements indicating that their view of the marriage debate had changed in favor of allowing Americans to marry regardless of gender. Only nine of the 53 Democrats in the Senate continue to oppose marriage equality in some way, and of those, few come down staunchly on the side of preserving the traditional one-man, one-woman definition.

Those nine senators are Heidi Heitkamp of North Dakota, Joe Manchin of West Virginia, Mary Landrieu of Louisiana, Joe Donnelly of Indiana, Mark Pryor of Arkansas, Tom Carper of Delaware, Bill Nelson of Florida, Bob Casey of Pennsylvania and Tim Johnson of South Dakota. Of the nine, some oppose DOMA, some have adopted a wait-and-see attitude, others are less specific.

Manchin's answer is straightforward: Spokesperson Katie Longo said that guided by his faith, Manchin "believes that a marriage is a union between one man and one woman" and wants to uphold DOMA.

Nelson is a more complicated case. In May 2012 he told the Miami Herald he believes the issue should be left to the states, but a spokesperson for his office told TIME this week that Nelson supports the one-man, one-woman vision of traditional marriage.

Some of those with more complicated stances on the issue tend to value a term President Obama once used to describe his views on gay marriage: "evolving."

"Senator Carper was proud to support Delaware's efforts to enact civil union legislation and earlier this month he joined 211 of his Congressional colleagues in co-signing the amicus brief that urges the Supreme Court to invalidate Section 3 of DOMA," a spokesperson for Carper told ABC News this week. "Like many Americans including Presidents Obama and Clinton, Senator Carper's views on this issue have evolved, and continue to evolve."

"Change" is another favorite.

"We'll have to see what the Supreme Court says about gay marriage," Landrieu told POLITICO on Tuesday. "And I just think that people's views about it are changing quite rapidly, a more progressive position. I'm just going to continue to talk to the people of my state."

An ABC/Washington Post poll released last week showed support for legal gay marriage among Americans had grown from 37 percent in 2003 to 58 percent. Almost 84 percent of Democratic Congress members signed an amicus brief for the Supreme Court asking them to overturn DOMA.

That said, not all those who signed the brief have come out in favor of legalizing gay marriage in their state - Carper, for example.

Even Republicans, typically a group staunchly opposed to gay marriage, have seen some switching up in the past month. More than 80 signed on to a similar amicus brief, led by former George W. Bush White House political director Ken Mehlman. Sen. Rob Portman, R-Ohio, announced his support for marriage equality earlier this month, and Wednesday, Sen. Lisa Murkowski, R-Alaska, announced she was "evolving" on the issue, after her Democratic counterpart, Sen. Mark Begich, endorsed it.

Political strategist Jason Johnson predicts the flood of politicians piling onto the other side isn't going to dry up any time soon. Any hesitancy to express support for same-sex marriage on either side of the aisle stems from uncertainty in how important gay marriage is to voters, according to Johnson.

"No one has been able to figure out with any effective consistency how gay voters vote and how straight voters vote on gay issues," Johnson told ABC News on Thursday. "It's very hard to determine what percentage of your population in your constituency are openly out gay voters and if gay marriage is their driving issue."

For Democrats, though, he said pressure is only going up.

"It's going to become a litmus test for Democrats and they're going to receive money pressure, and really at this point there's not much of a benefit … to standing against it, because it's the direction that the entire country is going in."