Senate Majority Leader Harry Reid, D-Nev., tried to discourage a group of Senate Democrats from sending a letter to President Barack Obama this week, concerned that its suggestions for solutions to the fiscal cliff would make Democrats appear divided.

Sen. Jay Rockefeller of West Virginia told fellow Democrats at a caucus lunch Wednesday that he was working on the letter and seeking signatures, sources said.

But Reid suggested that the letter, which was being organized by Rockefeller and Iowa Sen. Tom Harkin, would be a bad idea because it would give the impression that Democrats were not united on how to address the fiscal cliff.

“There are better, more productive ways to approach this issue,” said a senior Senate Democratic aide familiar with the issue.

The concern was that the letter would take the focus off of Republicans who are being pressured by Democrats and Obama to allow a raft of tax cuts to expire for households making more than $250,000 a year. Democrats want to extend tax cuts for the those making less.

The letter, which has yet to been sent, calls on Obama to strike a deal on the fiscal cliff that has a 1-to-1 ratio of tax increases to spending cuts. As of Wednesday night, it had at least 13 signatures, sources familiar with the letter said. A draft of the letter seen by Roll Call did not include the names of the other signatories.

Supporters of the letter hope to give Democratic leaders increased leverage going in to a meeting at the White House with Republican leaders by making clear the position of some of the caucus on how much new revenue the president should demand.

“These revenues must be real and not inflated by ‘fuzzy math’ like dynamic scoring,” the letter reads. “Any deal should end the Bush tax cuts for the wealthiest two percent of the population and close tax loopholes benefitting wealthy Americans and corporations. Furthermore any deal must include a one-to-one ratio of revenues to spending cuts.”

Obama rejected dynamic scoring in his press conference Wednesday.

Still, the letter lays down a marker for liberal senators as congressional leaders are set to meet with the president Friday. Congress must come to an agreement on a budget deal by the end of the year to avoid about $600 billion in tax increases and spending cuts that budget analysts say could throw the economy back into a recession.

The signatories also want to count the $917 billion in already-agreed-to cuts included in the deal to raise the debt ceiling in August 2011 as spending cuts in any new budget deal.

The senators also stressed that the process by which any deal is approved should be transparent.

“Members should not be forced to vote up or down on plan that they have not seen and have not been able to study,” the letter said. “We should have ample opportunity to comment on proposals being considered and all viewpoints from the liberal to conservative end of the spectrum should be considered.”