By Glen Johnson, Globe Staff

Richard Lugar’s loss in his Indiana Republican primary on Tuesday gave Senator John Kerry the chance to move up at least a slot in US Senate seniority. It also prompted the Massachusetts Democrat to vent anew against what he sees as increasing polarization in American politics. Lugar, who was the top Republican on the Senate Foreign Relations Committee after serving in the chamber since 1977, lost to state Treasurer Richard Mourdock, who had been backed by a Tea Party constituency.

By Bryan Bender, Globe Staff

The primary loss of Richard Lugar, a powerful voice of foreign policy for Republicans for three-plus decades, reshuffles the political deck for Indiana and beyond. For John F. Kerry, his Democratic counterpart on the Senate Foreign Relations Committee, the loss is both personal and professional. “This is a tragedy for the Senate and the loss is particularly felt by all of us who have been privileged to serve with Dick on the Foreign Relations Committee,’’ Kerry said in a statement minutes after Lugar lost the GOP primary to Richard E. Mourdock, the state’s treasurer.

By Callum Borchers, Globe Correspondent

Republican Senator John McCain of Arizona blasted President Obama on foreign policy Sunday, accusing him of mishandling relationships with countries throughout the Middle East.

McCain said the US should arm rebels in Syria to help them fight against the government of President Bashar al-Assad. “Absolutely. It’s an unfair fight,” McCain said on ABC’S “This Week. McCain downplayed the risk of arming a group of Syrian rebels whose long-term mission is uncertain.

By Callum Borchers, Globe Correspondent

Mitt Romney on Thursday blasted the Obama administration for its handling of Chinese dissident Chen Guangcheng, who said he felt coerced into leaving the safety of the US embassy in Beijing. Chen, who is blind, is a human rights activist who escaped house arrest last week and sought refuge at the American embassy. Romney accused the administration of putting talks about currency and trade, and the nuclear threats posed by Iran and North Korea ahead of Chen’s protection.

By Callum Borchers, Globe Correspondent

Ending a yearlong campaign and a weeklong farewell, former House speaker Newt Gingrich formally ended his presidential candidacy Wednesday in Arlington, Va. Repeating an earlier pledge, Gingrich said he would help presumptive Republican nominee Mitt Romney try to defeat President Obama. Gingrich devoted much of his exit speech to thanking his supporters, including former GOP presidential candidates Rick Perry and Herman Cain, and billionaire casino mogul Sheldon Adelson, “who single-handedly came pretty close to matching Romney’s super PAC.”

By Tracy Jan , Globe Staff

President Obama flew to Afghanistan for a surprise visit Tuesday that will culminate in a speech this evening during which he is expected to promote a strategic partnership he is signing with Afghan President Hamid Karzai. The speech to the American people will be televised live from Bagram Air Base outside Kabul at 7:30. The president is also expected to mention the one-year anniversary of the raid that killed Osama bin Laden, according to a White House pool report.

By Callum Borchers, Globe Correspondent

Mitt Romney paid Twitter tribute to President Obama Tuesday morning on the one-year anniversary of the raid that killed Al Qaeda leader Osama bin Laden. “I commend those who planned and conducted the bin Laden raid a year ago, and I applaud President Obama for approving the mission,” Romney tweeted. How much credit Obama deserves for the strike and whether Romney would have issued the same order have been hot topics since the Obama campaign released a controversial video.