Senate Democrats are trying to downplay a new Congressional Budget Office report that says that only 38 percent of the spending in the House economic stimulus plan would be available in its first two years.

Majority Leader Harry Reid (D-Nev.) insisted that Appropriations Chairman Daniel Inouye (D-Hawaii) “said that that report is wrong. It’s misleading. … The money’s going to go out much faster than that.”

Still, Reid left open the possibility that the Senate may need to tweak its version of the stimulus package to ensure the funding goes to work immediately. House committees are vetting their plan this week, while the Senate Appropriations panel marks up its package Tuesday.

“That’s what the markup process is all about. That’s … why we have committees,” Reid said. “If some of that money needs to be rearranged or different portions spent, that’s what will happen.”

The Senate Finance Committee is expected to mark up the tax relief portion of the economic package on Tuesday as well.

However, Senate Budget Chairman Kent Conrad (D-N.D.) said he believes the CBO report was troubling. He agreed with a reporter that the conclusions reached by the nonpartisan office undermined the Democrats’ goal of providing money for so-called “shovel-ready” construction projects.

“I don’t know what other conclusions one could reach,” Conrad said Tuesday. “I think we’ve got to go back and look at the package. … I think we’ve got to think very carefully how to restructure this so more of the money gets out in a timely way.”

Republicans agreed, and suggested the Senate would need to account for the CBO’s findings when crafting its plan.

“Regretfully, the stimulus package seems to be drifting … off in a different direction from what President Obama seems to be suggesting,” Senate Minority Leader Mitch McConnell (R-Ky.) said. “It’s our view that we need to try to craft this package in such a way that it is truly stimulative in nature and not exacerbate the problem that we all know exists.”

Yet one senior Senate Democratic aide said Republicans were overreacting and appeared to be looking for an excuse to oppose the package.

“CBO’s estimates are for the first version of the legislation and does not reflect ongoing improvements to the legislative language to speed up spendout rates,” said the aide. “Several of the critical elements of the package — totaling more than $500 billion — are designed to spend out almost entirely over the first two years of the program.”

Those elements include much of the $275 billion tax package, extended unemployment insurance and food stamp benefits, and other temporary measures totaling more than $160 billion designed to help states maintain social service programs while averting local tax increases, the aide said.