As Senate Republicans enter their second month of what Majority Leader Robert C. Byrd (D-W.Va.) grimly calls an "obstructionist . . . scorched-earth" strategy to thwart Democratic initiatives, Byrd is planning to strike back where it could hurt most.

For starters, Byrd is threatening senators with loss of recess time -- including a delay of their month-long August vacation and an indefinite postponement of the early-October adjournment target -- if Republicans continue to block action on Democratic proposals from arms control to campaign financing.

Moreover, he is serving notice he will keep the Senate working on legislation to overhaul congressional campaign funding laws -- with vote after vote to call attention to the stalling tactics -- even if it means delaying action on other popular measures, such as trade legislation.

"They're going to have to keep coming back to the lick-log," said the West Virginia lawmaker. "If the Republicans are going to obstruct and stall on the nation's business, they'll have to take the blame." As for the campaign bill, he added, "I'm not in any big hurry to put it aside."

Senate leaders often resort to such threats to bring discipline to the chronically undisciplined chamber -- a task that former majority leader Howard H. Baker Jr., now White House chief of staff, once likened to "pushing a wet noodle."

But Byrd has already shown a stubborn streak about Senate work habits that has resulted in what one colleague derisively called Friday morning "bed-check" votes to keep senators from sneaking away early for weekends. And with Republicans resorting to resourceful guerrilla tactics to challenge his leadership only six months after the Democrats retook control of the Senate, he has a lot at stake in terms of future capacity to retain control of the Senate agenda.

So far, the Republicans have blocked action on a defense authorization bill that includes "Star Wars" arms-control constraints opposed by the administration, in addition to stalling the campaign financing measure. In doing so, they have gotten around the Democrats' 54-vote majority, which has held together remarkably well, by resorting to filibusters that can be broken only by 60 or more votes. Using other tactics, they stalled a catchall bill for weeks of flogging as a "budget-buster."

By mustering the 34 votes necessary to sustain a veto, they have also hoisted warning flags over measures including the wrap-up spending bill if it includes arms-control provisions sought by the House.

They stood aside from drafting the Senate's version of a fiscal 1988 budget, contributing to difficulties in working out a budget compromise between the House and Senate, and Byrd fears a GOP filibuster if the budget produces legislation to raise taxes in any major way.

Regardless of whether Byrd follows through on the threats, his response to the GOP tactics, which he discussed in an interview, underscores the tensions building in the 100th Congress as it moves toward next year's campaign season, where control of the Senate as well as the White House will be at stake.

The GOP strategy aims in part at preventing the Democrats from using Congress as a platform for mounting a campaign focusing on their ability to produce results, especially when those results undermine the legacy of President Reagan and the Republican-led Senate of the last six years.

The Republicans are portraying themselves as protectors of the faith, outnumbered but not outmaneuvered, as they expose what they regard as weak spots in Democratic initiatives, such as "taxpayer" financing of senatorial campaigns and arms-control "meddling" just before an expected U.S.-Soviet summit.

Some Republicans hope to kill the Democratic plans outright; others, especially those who share some Democratic goals but disagree over the methods, as in the debate over campaign finances, want to force the Democrats to deal with their ideas and include them in a compromise.

But the Senate GOP as a whole exposes itself to charges of "negative" and "obstructionist" tactics, as Byrd is charging, after having invested six years in building a reputation as a constructive player in the Washington game.

It is a risk that has not gone unnoticed by Sen. John F. Kerry (D-Mass.), chairman of the Democratic Senatorial Campaign Committee for next year's elections, who said the Democrats intend to focus in a major way on the GOP tactics as they prepare for the 1988 campaign. "They {Republicans} are playing a very risky game," Kerry said. "This isn't governing . . . this is obstruction."

Some Republicans are apprehensive about being tagged as obstructionists. Although Minority Leader Robert J. Dole (R-Kan.) continues to insist on blocking movement on the defense-with-arms-control bill, some Armed Services Committee members have indicated they would feel more comfortable if the Senate could at least move to consideration of the measure.

On campaign finance revision, Dole has stuck with Republicans who oppose spending limits and public financing, but has stressed his desire for a bipartisan compromise with Byrd.

The GOP strategy could be particularly tricky for Dole in his expected bid for the Republican presidential nomination. Having worked hard to lose the "hatchet-man" image, he has earned a more recent reputation as an achiever of results. And on campaign finance revision, he is expected as a presidential candidate to take public financing that he is trying to bar for senatorial campaigns.

There are also risks for the Democrats, especially now that Byrd has decided to join the Republicans in hardball tactics that call for a degree of group discipline and self-sacrifice that does not always come naturally in the Senate.

Byrd's strength thus far has been the unanimous and near-unanimous votes of Senate Democrats on key issues. If Byrd has to deliver on his threats, he could find trouble in his own ranks. Democrats who were restive over bed checks on Fridays may not take kindly to hanging around through August or doing their Christmas shopping during quorum calls.