The Hill reports that some Democratic senators up for re-election have declined to back President Obama's gay marriage statement.

Sens. Jon Tester (Mont.) and Claire McCaskill (Mo.), the two most vulnerable Democratic senators, have declined to endorse Obama's call for the legalization of gay marriage.

Sens. Joe Manchin (W.Va.), Bob Casey (Pa.) and Bill Nelson (Fla.), Democrats who have easier races but in states that could become more competitive by November, have also backed away from Obama's stance.

They all represent states with constitutional amendments or laws banning same-sex marriage.

Senate Majority Leader Harry Reid (D-Nev.) predicted Thursday the Democratic Party would adopt a pro-gay marriage plank in its platform. While that may happen when delegates to the Democratic National Convention meet September in Charlotte, N.C., the party remains divided.

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"It comes down to independents, who make it somewhat of a swing state. Generally the independent vote in Montana is more conservative and Republican-oriented than Democrat-oriented," he said.

"[Rep.] Denny Rehberg's strategy is to tightly link Tester and Obama," he added, in reference to Tester's opponent.

Lobach said it would be a "political mistake" for Tester to match Obama's stance on gay marriage.

Sen. Claire McCaskill (D-Mo.), who has been one of Obama's closest allies in the Senate, has also kept her distance.

Her spokesman declined to endorse the president's position. In an email to the Springfield News-Leader, John LaBombard said, "Claire recognizes this is a very personal issue for many Missourians" and said she thinks states should "take the lead in determining marriage equality."

Obama may be trying to finesse the issue but that won't stop activists from trying to put a pro-gay marriage plank in the party platform at the convention. It's not an issue that is going to split the party, but it will make riveting viewing if a floor debate on the issue is allowed. The Obama team will seek to avoid that situation but they may not have a choice. Conventions have a way of spinning out of control at times, even if the incumbent president thinks he has an iron grip on the proceedings.

Meanwhile, Tester and McCaskill probably won't be inviting the president to campaign with them anytime soon.