WASHINGTON — Matt Romney, a son of the Republican presidential nominee, traveled to Moscow this week seeking Russian investors for his California-based real estate firm just days before his father is to wrap up a campaign in which he has vowed to take a tougher stance with the Kremlin.

Mr. Romney, the second-oldest son of Mitt Romney, met with Russians whom he hoped to convince to invest in his company, Excel Trust, which owns shopping centers across the United States, the firm said. Although the company’s focus has been solely domestic, it said it has begun exploring international opportunities to raise funds.

Mr. Romney’s trip a week before the presidential election underscored the complex relationship between his family’s business and the political campaign. Mitt Romney has criticized President Obama for being too soft on Russia, calling it “our No. 1 geopolitical foe” and promising to confront President Vladimir V. Putin’s government with “more backbone” if elected on Tuesday.

Mr. Romney has criticized Mr. Putin’s crackdown on domestic dissent and opposition to stronger international measures against Syria and Iran. He has assailed Mr. Obama for not doing more to defend human rights in Russia and for signing a nuclear arms reduction treaty with Moscow.