With a brief return to the Senate, Cruz claimed progress on a series of measures that are likely to appeal to Republican primary voters in the hotly contested campaign. He wrote a letter to President Obama on North Korea policy, voted for sanctions on North Korea and co-sponsored a bill to enforce fines on undocumented immigrants. The third move may help the senator from Texas bolster his record on immigration compared with presidential rival Donald Trump, whose campaign has made the issue a rallying cry.