The top Democrat and top Republican in the Senate agreed Thursday to swear off seeking major changes to rules in the chamber in this Congress — and the next one.

Majority Leader Harry Reid (D-Nev.) announced a series of rules changes for the Senate on which he struck an agreement with Minority Leader Mitch McConnell (R-Ky.), among them an agreement to not seek changes to the filibuster or other rules.

"We've agreed that I won't force a majority vote to fundamentally change the Senate … and he won't in the future," Reid said in remarks early Thursday afternoon on the Senate floor.

Reid was referring to the so-called "constitutional option" that Democrats had sought to use in order to force changes to the filibuster, an effort that they had abandoned despite much saber-rattling by reform-minded liberals.

Under that option, Democrats would have sought reforms by using a simple majority vote, reasoning that, on the first formal day of a new session, the Senate can change its own rules with a majority instead of the 67 votes normally needed to change a rule.

But Democrats never seemed able to reach an agreement on the scope or type of changes, and Reid announced a more modest set of changes on which the parties would vote Thursday afternoon.

The reforms include an end to secret holds, a reduction in the number of presidential nominations subject to the lengthy Senate confirmation process, an end to mandatory readings for amendments if they've been publicly available for at least three days, an agreement by Republicans to limit their filibusters of motions to begin debate, and an agreement by Democrats to limit instances in which they "fill the tree" — or limit the number of amendments Republicans can put to a given piece of legislation.

Perhaps the most significant agreement was that of changing the filibuster, the principal tool of the minority to stall or block legislation. Republicans used the tactic to great effect in the last Congress, though Democrats griped that the process had been abused at an unprecedented level.

Some senior Democrats had been skittish about changing the rules to weaken the filibuster and making it easy for the majority to move items through the chamber, especially since Republicans are likely to make a strong move to regain the majority in the Senate in the 2012 elections. McConnell's agreement ensures that, at least for the next Congress, the GOP wouldn't move to undercut Democrats' rights should they reclaim the majority in two years.