Congressional aides briefed by the administration said the planned moves would be a forceful increase in pressure on Russia but not a full-scale economic attack. While the plans will not assuage some lawmakers who have called for tougher action, the aides said they would go a long way toward satisfying many.

Whether the Europeans would go along remained an open question. American officials expressed optimism that they were finding common ground with the allies but recognized that it was unlikely that the European Union, with 28 member states that operate by consensus, would take the same actions as the United States. The Europeans may also move to defer the toughest steps.

European Union foreign ministers met to discuss Ukraine on Monday. When European heads of state meet on Friday, crucial to any decision will be Chancellor Angela Merkel of Germany, whose country has extensive energy and economic ties to Russia. Mr. Obama spoke last Friday with Ms. Merkel as well as with President François Hollande of France to press for continued unity. Vice President Joseph R. Biden Jr. called President Petro O. Poroshenko twice in two days.

American officials were urging their European counterparts not to give too much credit to Mr. Putin for positive statements in recent days. Twice before, the Americans argued — in April and then again this month when he attended a D-Day commemoration in France — Mr. Putin has seemed to embark on what they called a “charm offensive” to deflate any momentum within the European Union toward tougher sanctions.

If the Europeans are not willing to impose new sanctions after Friday’s meeting, the American side hopes to reach agreement on a package that would be ready to use if Mr. Putin does not follow through on his recent positive statements or reverts back to more hostile actions once the meeting has passed. In effect, that would make the sanctions package a deterrent.

Some analysts said the support for sanctions has diminished in Europe. Macro-Advisory Ltd., a consultant firm in Moscow, told clients that there might be “so-called scalpel sanctions later this week” but predicted that “the emergence of political pragmatism in Kiev and Moscow” would avert “more serious trade- and economy-disrupting sanctions.”

The drive for more sanctions comes as American businesses are growing more vocal in protesting the possibility that the United States may act on its own. While lobbying the White House and Congress quietly until now, leading business groups plan to start a wide advertising campaign voicing their concerns.