Organized labor suffered its second staggering blow in as many days yesterday as the Carter administration endorsed a minimum wage increase substantially lower than labor wanted and a congressional subcommittee proposed.

Still reeling from the House defeat Wednesday night of a bill to expand unions' picketing rights on construction sites, AFL-CIO lobbyists were stunned and angered when Labor Secretary Ray Marshall unveiled the administration's minimum wage position before th House Labor Standards Subcommittee.

"The administration's proposal is shameful . . . a bitter disappointment to everyone who looked to this administration for economic justice for the poor," said AFL-CIO President George Meany in his administration he helped elect.

The one-two blow from the Democratic Congress and Democratic White House raised grave questions about labor's ability to cash in on its political debts with both the administration and Congress. It appeared to signal deep trouble for labor's entire program this year-the year in which it planned to make historic breakthroughs in labor legislation.

In his testimony, Marshall proposed raising the present $2.30 per hour wage floor to $2.50 on July 1 and pegging future annual increases to 50 per cent of average straight-time earnings in manufacturing. Marshall estimates this would mean $2.73 by July, 1978, and $2.92 by July, 1979.

The administration proposal met labor's request for automatic annual increases, as opposed to the present practice of fixing the minimum wage by congressional action every few years, but it feel far short of the actual levels that labor sought.

The AFL-CIO, supported by other unions, Called for an immediate $3 wage minumum, with future increases based on 60 per cent of manufacturing wages including overtime pay. Depending on actual wage levels, this could mean $3.30-by next January, said Clara Schloos, the AFL-CIO's minimum wage expert.

Subcommittee Chairman John H. Dent (D-Pa.) had introduced legislation that would provide $2.85 this year and 60 per cent of manufacturing wages thereafter.

Marshall said the administration bill would trigger wage increases for 4 million workers. The sub committee estimated its bill would give increases to 8 million workers. The total work force is more than 90 million.

Dent sharply critized the administration's proposal, saying he found it "just impossible to see how economists of the administration could sit down and come up with something so out of line with people's needs." Rep. Phillip Burton (D-Calif.) called it a "mincing and really completely indifensible proposal."

The most favorable comment came from Rep. Albert H. Quie (R-Minn.), who had advanced a plan similar to the administration's last year. However, another Republican, Illinois Rep. John N. Erlenborn, attacked the automatic escalator provision as a "mindless, thoughless formula," indicating that the administration proposal will catch flak from both sides.

An industry lobbyist put it this way: "The administration treid to compromise and wound up pleasing no one."

There was not even agreement within the administration on the minimum wage. Marshall advocated a wage level closer to the Dent bill but was overruled, reportedly by most if not all of Carter's other top economic advisers. "If it hadn't been for Marshall, we understand we wouldn't have gotten anything," said an AFL-CIO official.

According to one subcommittee source, the legislation that will go to the House floor - probably next month - is likely to reflect a compromise between the Dent bill and the administration position.

Minimum wage legislation in some form is considered to have broader support in Congress than the picketing bill, although that, too, at one point was considered to be safe in the House.

The U.S. Chamber of Commerce, in a statement hailing the 217-205 House vote against the bill to permit a single union to picket and thus possibly shut down an entire construction site, said the wage legislation is "fairly popular" and thus the "most difficult" of the labor proposals to fight. Some lawmakers will be under Pressure to "give the unions something as the session goes on," said Hilton David, a chamber vice president.

Even by labor's own reckoning, its lobbying for the so-called common situs picketing bill was a disaster. "We took the House for granted," said Victor Kamber, chief aide to Robert Georgine, president of the AFL-CIO's building trades department, thus enabling the construction industry and National Rights to Work Committee to mount an effective campaign against it.

House Speaker Thomas P. O'Neill, acknowledging that the vote was a defeat for the Democratic House leadership as well as labor, said the Democrats' own vote count showed the bill was in trouble early this week. He said labor insisted it had the votes, so he went along. He said he had not seen so much mail on an issue since the peak years of the Vietnam war.

Several union leaders interviewed yesterday said the defeat, along with the setback from the administration will prompt a redoubling rather than a slakening of union effort on behalf of its other measures, including minimum wage, repeal of right-to-work laws and strengthening of union organizing legislation. "We know now where our work has to be done." said William DuChessi, lobbyist for the textile workers.

But O'Neill said he does not intend to schedule the right-to-work repealer for a vote and doubts the Senate will act on it either. Said O'Neill: "It's an old rule of politics that you should not field the team unless you will win."