Is trashing the Koch brothers a winning issue for Democrats?

Senate Majority Leader Harry Reid, D-Nev., is nothing if not consistent. It's been more than a month since he began using floor time on the Senate to bash billionaire brothers Charles and David Koch (pronounced "coke") for using their extensive fortune to boost conservative candidates and causes.

And yet, Reid manages to carve out time almost every single day to target the brothers. Thursday's missive on the Senate floor charged that the Koch's "are single-handedly funding an attack on the nation's middle class" by focusing solely on electing Republicans who will help them get richer.

The daily Koch talk has gotten the majority leader's creative juices flowing. In the last few weeks, he has charged the Republican Party is "addicted to Koch," said that the budget authored by Rep. Paul Ryan, R-Wis., is a "modern Koch-topia," and designed a line of blazers that Republicans could use to show off their allegiance to Koch Industries.

"He knows very well that you always need a foil in politics," said Jim Manley, a former aide to Reid. The Koch brothers "are going to provide a good contrast" between the policies begin offered by the Democrats (focused on things like the minimum wage, equal pay and unemployment insurance) and those that the brothers advocate for.

And, Manley added, it's personal for Reid.

"I think its driven by the fact that he really is upset at the idea that two billionaires are trying to buy elections left and right without having the guts to do so publicly," he said.

The strategy is, unsurprisingly, unpopular with Republicans, who accuse Reid of trying to distract voters from the problems with the Affordable Care Act. It even brought the Koch brothers out of the woodwork: last week, Charles Koch wrote an op-ed in the Wall Street Journal that suggested Reid was engaging in character assassination and defending the jobs Koch Industries has created and the awards it has won.

But the critics are expanding into Reid's own party which could give him a reason to tread carefully. On Fox News Thursday morning, Sen. Joe Manchin, D-W.V., suggested Reid had gone too far.

"They're not breaking the law. They're providing jobs," Manchin added, noting he doesn't agree with their politics or philosophy. "There's people that don't like the extreme Democrat politics or extreme Republican politics. We've got to start being Americans again."

"You don't beat up people," he said.

John Feehery, a former GOP congressional aide, noted that Republicans tried to turn liberal billionaire George Soros into a campaign issue in 2006.

"That didn't work out for us very well either," Feehery said. The Republicans lost control of both the House and Senate that year.

"It distracts the Democrats from issues that might actually resonate with the voters," Feehery said.

In other midterm campaign news:

Keystone XL pipeline: Democrats have been relatively unified in their messaging push this year, but 11 Senate Democrats are now pushing the president to fulfill a major GOP wish list item and approve the Keystone XL pipeline.

Five of those lawmakers have tough re-election races this year, including four red-state Democrats: Sens. Mary Landrieu of Louisiana, Kay Hagan of North Carolina, Mark Begich of Alaska and Mark Pryor of Arkansas.

In a letter to the president, the lawmakers have asked for a decision on the pipeline no later than May 31. The decision they want to see is an approval.

"We cannot miss another construction season, given the long cold winter this year along the Keystone XL route and the time required for ground thaw, we could be looking at a very short season," the letter says. "WE ask that you bring this entire process to an end no later than May 31, 2014, and that your final decision be the right one, finding that the Keystone XL pipeline is in the national interest."

They note that a State Department review issued earlier this year concluded the pipeline would not significantly worsen carbon pollution.

Of course, environmentalists remain actively opposed to the pipeline and the president can hardly give Democrats a reason to stay home in November.

Following the political winds: Sen. Angus King, the independent from Maine, is playing hard to get ahead of the midterm elections.

King has chosen to caucus with the Democrats along with fellow independent Bernie Sanders from Vermont, giving them an effective 55-seat majority. But King told The Hill newspaper earlier this week that's not a done deal if Republicans take over the chamber in November.

"I'll make my decision at the time based on what I think is best for Maine," King said. He made clear after the 2012 elections that being in the majority matters to him, which led him to caucus with Senate Democrats - and could provide the reasoning to do it again. It would certainly increase his prospects of getting the best committee assignments.

Republicans need six seats to take over control of the Senate in November. If they only pick up five, King could be the Republican's 51st vote, tipping the balance in their favor (a 50-50 tie would go to the Democrats; ties are by the vice president, in this case Democrat Joe Biden).