"Unless the administration gets OPEC to increase oil supply, American consumers are going to be in for a scorching summer of $4 gasoline with no relief in sight," Schumer said.
House Speaker Nancy Pelosi, D-Calif., agreed that people "need this rebate to cope with the rising cost of gas and groceries." She said that, while the rebates would help to get the economy moving, there was a need for a second stimulus package "and we have begun some conversation with the administration and Republicans."
As he had earlier in the week, Bush used the word "slowdown" to describe the state of the economy. He has denied that the nation is in a recession, although many economists say it is.
"It's obvious our economy is in a slowdown. But, fortunately, we recognized the signs early and took action," Bush said.
The rebates - up to $600 for an individual, $1,200 for a couple and an additional $300 for each dependent child - are the centerpiece of the government's $168 billion stimulus package, enacted in February. Roughly 130 million households are expected to get them.
Bush made the comments before boarding his helicopter at the start of a day trip to Connecticut.
People must file a tax return for their 2007 income to be eligible for a rebate check.
The IRS now says all checks for those who filed tax returns on time are scheduled to be deposited or mailed by July 11.
The economy - burdened by the collapse of home prices, a financial and credit crisis, and now rising energy and food prices - grew at an anemic 0.6 percent in the final three months of last year and is believed to have gotten even weaker in the first three months of this year.
The government will report on the first quarter's performance next week.
With the economy faltering, the nation's unemployment rate has climbed to 5.1 percent, the highest since September 2005, when it suffered from the devastating blows of the Gulf Coast hurricanes. Job losses in the first three months of this year neared the quarter-million mark.
Foreclosures have surged to record highs and financial companies have taken multibillion losses on mortgage investments that soured. The situation has sent a tremor through Wall Street and has sent the administration, Congress and presidential contenders looking for ways to provide relief.