One of Hillary Clinton's main rivals is trolling her with a letter from her past

Back in 2008, Hillary Clinton asked her rival in the presidential election, then-Sen. Barack Obama (D-Illinois), to participate in more debates than he wanted.

This time around, it's Clinton who is getting challenged to participate in more debates. And one of her rivals is pointing to her past push to put pressure on her to engage.

Former Maryland Gov. Martin O'Malley (D) has been attacking the Democratic National Committee for sanctioning only six presidential debates. O'Malley, who is far behind Clinton in the polls, has described the situation as "rigged" and "undemocratic."

In a statement to Business Insider, O'Malley's deputy campaign manager, Lis Smith, said his team is "completely in agreement with Secretary Clinton's comments in 2008."

"Given the conviction with which Secretary Clinton's campaign stated the need for more debates in 2008, we have no doubt that they will echo these calls again in 2016," Smith said.

The Clinton campaign did not respond to a request for comment about Smith's statement.

Clinton's former campaign manager Maggie Williams asked for more debates in a letter to her Obama campaign counterpart, David Plouffe, that was sent on April 26, 2008.

At the time, the Democratic candidates had participated in more than 20 debates, but Obama declined to appear at one in North Carolina, where he was leading in the polls.

"The American people are choosing a direction for their children and families. They have a right to hear from those who want to be their leaders. Our Democratic primaries reflect the keen interest of the American citizenry in this election," Williams wrote.

Williams argued only a small number of the debates featured Obama and Clinton, the two primary finalists, facing off directly.

"I understand that Senator Obama has raised the point that there have already been more than 20 debates this election cycle. However, only four of those have been between Senator Obama and Senator Clinton. We can all agree that many important issues have received scant attention during previous debates, including such important topics as education and the energy crisis," she wrote.

Specifically, Williams asked for Lincoln-Douglas style debates rather than the moderated discussions traditionally featured during presidential races.

"Senator Clinton and Senator Obama will participate in a 90-minute debate in an open public forum. Just the two of them - no questioners, no panelists, no video clips. One candidate would speak for two minutes, then the other, alternating back and forth all the way through the debate," Williams wrote.

Obama declined the Clinton campaign's request.

Smith quoted from Williams' letter in her statement.

"We are completely in agreement with Secretary Clinton's comments in 2008 - the American people 'deserve more' and we need debate! In fact, like Secretary Clinton then, Governor O'Malley believes we should emulate the spirit of the Lincoln-Douglas debates, that political debates are 'are a vital part of our democratic process,' and that voters in every state should have the opportunity to hear from candidates - in a robust way - before they vote," she said.