Despite Democratic complaints that Republicans were trying to sink the Senate’s landmark ethics bill last week, GOP leaders were working toward a very different end: sending a message to the Democrats that they still wield power and have the know-how to disrupt the majority agenda.

Senate Minority Leader Mitch McConnell (R-Ky.) — with a strong assist from Minority Whip Trent Lott (R-Miss.) and Budget ranking member Judd Gregg (R-N.H.) — picked a high-profile fight with Majority Leader Harry Reid (D-Nev.) by insisting on a vote for line-item veto authority.

The move led to a standoff with the Democrats and charges that each side was holding up the ethics bill.

In the end, Reid won overwhelming passage of the historic ethics measure, while Republicans got their vote on the line-item rescission authority this week when the Senate considers a hike in the minimum wage.

But the brief impasse sent the most public message yet that the Republicans will not get bowled over in a 51-49 Democratic majority.

“It was the first major test of how we can act as an effective minority,” noted a senior GOP leadership aide. “We have to start out with our best foot forward.”

The aide added, “We’re going back to the fundamentals — blocking and tackling.”

While the bill ultimately passed by a hefty 96-2 margin, the Republicans didn’t walk away completely unscathed.

Democrats and public interest groups pounced on the GOP for trying to kill the ethics and lobbying measure by insisting on an amendment that was completely unrelated to the underlying bill.

Privately, however, Democrats acknowledged that GOP leaders were laying down a marker that they would not simply roll over and indicated it was the opening salvo in an under-the-radar war for practical control of the chamber.

“We were expecting something. If it hadn’t been the line-item veto, it would have been any number of poison pills,” said a senior Democratic leadership aide, who characterized the line-item amendment as “a stalking horse for a larger struggle over who is going to run the Senate.”

GOP aides said the Republican leadership made a strategic decision to draw the line in the sand over the issue. And while they didn’t orchestrate it simply as a way to exercise minority strength, it ended up that way, they said.

As one Republican aide noted: “It made sense to do this, but of course the element overlying everything is, who is going to set the tone? Is it Harry Reid? Or, is a vigorous minority going to set the tone?”

The aide added that while “it’s not about flexing muscle for the sake of flexing muscle,” Republicans aren’t going to be pushed around by Senate Democrats or by Harry Reid.”

It doesn’t hurt the Republicans that McConnell and Lott have served in the minority before and understand how to employ procedural tactics to block the majority.

Lott, in particular, is in a unique position to help the GOP minority since he served as Minority Leader for a brief period in 2001 when then-Sen. Tom Daschle (S.D.) led the Democrats under the same 51-49 party split.

“Republicans wanted to make the point that they have 49 votes, and that they have a say in legislation and we can set an early precedent,” one senior Senate Republican aide said. “There was a concerted decision to make a stand on this. The point was to be heard when we need to be heard, and show our teeth.”

The stage has been set for upcoming Senate fights over controversial bills — including later this week when the chamber takes on the long-awaited minimum-wage increase — and down the line when Democrats take up changes to the Medicare prescription drug law.

Reid already has agreed to compromise on the minimum-wage measure by adding some business tax breaks, and now he also will allow a vote on the line-item amendment.

When asked last week whether the ethics showdown was one of many battles to come, Reid said he didn’t know, but acknowledged that Republicans “aren’t wild about anything I’ve talked about.”

“I think they’re going to pick their spots,” the Democratic leadership aide said.

Reid, a veteran lawmaker who served as Minority Leader in the previous Congress, is well-prepared for the difficult road ahead as he tries to pass a Democratic agenda with just a two-seat advantage.

Reid served as Majority and Minority Whip under Daschle before ascending to the top job in January 2005.

Democrats said Reid fully understood the undercurrents of the GOP line-item fight. For instance, an aide to one rank-and-file Democratic Senator noted that Reid and other Democratic leaders made a strategic move to resurrect Republicans’ “obstruction” mantra to counter McConnell’s move, choosing to focus on the practical and political implications of the fight, rather than its substance.

Similarly, the Democratic leadership aide said an understanding that these fights will continue throughout the 110th Congress drove Reid’s efforts to portray the final agreement allowing a cloture vote on the line-item amendment this week as a win for neither party.

Reid had “two options — blast away at Republicans or, despite what went on, to demonstrate a willingness to continue to work with Republicans,” this aide said. “He could have gone and gloated” that he secured passage of the bill without the amendment, but the Democratic leader instead opted to take a more neutral approach, the aide argued.