During his visit to Washington over the weekend, Polish Prime Minister Donald Tusk took home with him a US promise to help modernize Poland's military in exchange for a deal to host the US base.
Polish Foreign Minister Radoslaw Sikorski said the visit marked a new level of Poland-US relations.
Washington has also made some headways in winning over the Czech Republic. After three days of bilateral talks last week, the two sides are likely to sign a bilateral treaty that creates a legal framework for the status of the US soldiers on the Czech soil at the planned US radar base in early spring, the Czech Defense Ministry said in a statement.
Czech deputy prime minister for European affairs, Alexandr Vondra, on Monday described as "advantageous" a deal with Washington on the US radar base in his country.
Vondra also said Poland should not "wait for a new US administration" to strike a deal, although some 70 percent of Czech citizens reject the plan.
As the Bush administration moved closer to a deal with Poland and the Czech Republic on the controversial missile shield, it has become all the more urgent for Washington to seek some grudging concessions from Moscow over the issue.
The scheduled visit apparently is aimed at easing rising tensions between Moscow and Washington. Russian President Vladimir Putin and his US counterpart George W. Bush agreed in a telephone call last week that the visit, a follow-up to a similar round last October, would be "a good idea," White House spokeswoman Dana Perino said.
Rice and Gates are expected to meet with their counterparts and seek talks with Putin and president-elect Dmitry Medvedev.