President Obama's ambitious second-term agenda could hit roadblocks in the Senate, where vulnerable red-state Democrats up for re-election may be unwilling to support his plans for increased gun control, immigration reform, higher spending and taxes, and other liberal proposals.

Obama's wish list, outlined in Tuesday's State of the Union address, included legislation to ban assault weapons, a "cap and trade" proposal to reduce greenhouse gas emission, higher taxes and a plan to raise the federal minimum wage to $9.

While Democrats cheered frequently during the speech, for some, the proposals present political danger. Analysts believe nine Democratic Senate lawmakers will face challenging re-election battles, most of them from red states including Arkansas, Alaska, Minnesota and North Carolina, where voting for many of Obama's ideas, particularly a tax on carbon emissions or major gun control initiatives, could be career-ending.

If Senate Democrats lose a net six seats, their Republican opponents will win the majority in 2014.

The equation leaves Sen. Majority Leader Harry Reid, D-Nev., in the tough position of having to protect his party's control of the chamber while trying to win approval for Obama's priorities.

"Some of the president's key ideas will be hard to pass because it will be difficult to keep the entire Democratic caucus together," said Nathan Gonzales, deputy editor of the Rothenberg Political Report.

Sen. Lamar Alexander, R-Tenn., said, "I think the hardest job for Democrats to defend in 2014 is why we are not doing anything about the debt, or about the Medicare program that is not going to be able to pay the hospital bills in a few years."

In North Carolina, Republicans are determined to defeat Sen. Kay Hagan, a first-term Democrat. The state voted for Obama in 2008 but in 2012 switched back to red, backing Mitt Romney. Hagan is polling only slightly ahead of a list of potential opponents.

Obama probably won't be able to count on Hagan's support for legislation on major gun control, cap and trade or raising the minimum wage, state political experts say.

"She's just got to watch her step," said East Carolina University political science professor Thomas Eamon. Hagan may also steer clear of Obama's proposal to raise the minimum wage because of North Carolina's lack of union support and 9 percent unemployment.

Sens. Al Franken, D-Minn., Mark Pryor, D-Ark., Mary Landrieu, D-La., Max Baucus, D-Mont., Mark Begich, D-Ark., and Tim Johnson, D-S.D., could also run into political trouble by backing a gun control bill.

Begich and Landrieu, hailing from oil-rich states, are also unlikely to back a cap and trade plan or Obama's plan to increase taxes on oil and gas producers.

Franken, who narrowly won his first term and is up again in 2014, waffled on gun control earlier this year but has since signed onto the Democratic plan to ban assault-style weapons and high-volume magazine clips.

Facing a powerful gun lobby in his state, Franken may be spared an actual vote on the gun bill.

That's because Reid has refrained from endorsing the proposal and said if it makes it to the floor for a vote, he'll leave it open to an amendment process that would almost certainly weaken it.

Baucus, who is seeking his seventh term, has only a 3-point advantage over a GOP challenger. He has not committed to backing any new bans or background checks. "I will look closely at all proposals on the table, but we must use common sense and respect our Constitution," he said in a statement.