Washington ? So far this year, Congress has done what it does best — spend a lot of money and make a lot of promises.

Now, as lawmakers return from a two-week spring break, comes the hard part — the actual crafting of legislation that will change how banks are regulated, health care is delivered and the nation consumes energy.

Over the next five weeks, leading up to the Memorial Day break, much of the action will come not in the full House or Senate, but in committee rooms.

The Senate Finance Committee on Tuesday holds the first of several public discussions on the seminal issue of this congressional session, overhauling the health care system. The House Energy Committee is expected to vote soon on climate change legislation that could include a cap-and-trade system for carbon emissions.

The House Financial Services Committee may vote in May on far-reaching rules aimed at averting a repeat of the financial meltdown, according to the chairman, Rep. Barney Frank, D-Mass.

“We’re laying the groundwork for the expected battles to come on energy, education and health care,” said Jim Manley, spokesman for Senate Majority Leader Harry Reid, D-Nev.

In coming weeks, lawmakers must reach a compromise on that budget plan and take up a big-money item: a White House request for $83 billion to finance military and diplomatic operations in Iraq and Afghanistan through the fall.

The Senate’s legislative calendar, never predictable because of the minority’s powers to delay bills, could be slowed by GOP opposition to several Obama administration nominees.

A showdown could come this week over Christopher Hill, President Barack Obama’s choice to be ambassador to Iraq. Sen. Sam Brownback, R-Kan., was critical of Hill’s performance when the diplomat was the Bush administration’s top negotiator with North Korea and has pledged to slow down the process leading up to a vote on the nomination. A first procedural vote is set for Monday.

Obama’s nominee to be health secretary, Democratic Gov. Kathleen Sebelius of Kansas, could face a rocky road to confirmation because of her abortion rights views. The Senate Finance Committee scheduled a Tuesday vote on whether to send her nomination to the full Senate.